Hoarding behaviors appear quite often among people with dementia, occurring in 15–49 % of dementia cases (Hwang, Tsai, Yang, Liu, & Lirng, 1998; Hwang, Yang, Tsai, & Liu, 1997; Marx & Cohen-Mansfield, 2003; Sinha et al., 1992). People with dementia may hoard because they are unable to discriminate among objects and therefore they are unable to decide what to discard or to keep (Stein, Seedat, & Potocnik, 1999). People with dementia may give the same reasons for hoarding possessions as people who hoard without dementia give. However, people with dementia often explain their hoarding behavior in ways that reflect the decline in general cognitive processes. For example, people who hoard with dementia report saving possessions because they fear others will steal them. They report saving food that is outdated because they believe it is still edible. Furthermore, people with dementia can agree to relinquish possessions but later forget they gave permission and accuse others of stealing them.

There does not seem to be much difference between what people with dementia save and what people who are cognitively intact and hoard save. For example, case reports note that people with dementia and people with hoarding disorder save ordinary possessions, human waste products, or spoiled food (Hwang et al., 1998; Pertusa et al., 2008).

Because hoarding and hiding behaviors are common among those with dementia (Marx & Cohen-Mansfield, 2003), it is useful to assess cognitive function in older adults who present with hoarding behaviors. Dementia-screening procedures are described in Chap. 6 (Assessing Harm Potential) and interventions for dementia-driven hoarding behaviors in Chap. 10 (Special Populations).

Diogenes Syndrome is a condition characterized by extreme self-neglect, domestic squalor, social withdrawal, and lack of concern about one’s living conditions (Cooney & Hamid, 1995). Hoarding behavior is often a feature of Diogenes Syndrome and perhaps one of the first terms investigators used to describe hoarding behavior (Clark, Mankikar, & Gray, 1975). Typically, Diogenes Syndrome affects older adults. Researchers and clinicians sometimes refer to this condition as senile breakdown. Often, older adults who present with this syndrome have no classifiable psychiatric condition (Clark et al., 1975). Other times, however, the self-neglect, squalor, isolation, and hoarding behavior common to Diogenes Syndrome are manifestations of Alzheimer’s disease and other forms of dementia (Baker, Raetz, & Hilton, 2011; Hwang et al., 1998; Marx & Cohen-Mansfield, 2003; Wrigley & Cooney, 1992) or other mental conditions, such as schizophrenia (Greenberg, Witzum, & Levy, 1990; Hogstel, 1993; Thomas, 1997). Although hoarding behavior in these cases can cause problems, particularly for caregivers, they typically do not result in the same degree of accumulation as seen in hoarding disorder. Diogenes Syndrome is largely synonymous with extreme-self neglect and researchers question whether the term Diogenes Syndrome is still appropriate or useful given the development of our understanding of hoarding disorder (Marcos & Gomez-Pellin Mde, 2008).

Self-neglect is the inability (intentional or nonintentional) to maintain a socially and culturally accepted standard of self-care with the potential for serious consequences to the health and well-being of the self-neglecters and perhaps even to their community (Gibbons & Lauder, 2006). The behaviors and characteristics of self-neglect include unkempt personal appearance, poor nutrition, hoarding items and pets, neglecting household maintenance, living in an unclean environment, poor personal hygiene, and eccentric behaviors (Pavlou & Lachs, 2006; Smith et al., 2006). While the relationship between hoarding behaviors and self-neglect is unclear, investigators generally see one as a risk factor for the other. In addition to the squalid conditions that are common in both hoarding and self-neglect situations, they share other features. Several studies have documented significant functional impairment and social isolation among self-neglecting older adults (Pavlou & Lachs, 2006). In addition, investigators have reported that self-neglecting older adults exhibit significant executive function deficits (Dong et al., 2010; Schillerstrom, Salazar, Regwan, Bonugli, & Royall, 2009), which is also common in those with hoarding behavior (Grisham, Brown, Savage, Steketee, & Barlow, 2007; Grisham, Norberg, Williams, Certoma, & Kadib, 2010; Hartl, Duffany, Allen, Steketee, & Frost, 2005; Mataix-Cols, Pertusa, & Snowdon, 2011). Certainly, not all self-neglect cases involve hoarding behaviors and not all cases of hoarding result in self-neglect. However, it is possible that one acts as a risk factor for the other.

Squalor or severe domestic squalor is another term investigators use interchangeably with Diogenes Syndrome (Snowdon, Shah, & Halliday, 2007). Squalid home environments and neglect of hygiene is frequently mentioned in reports of older adults with hoarding behaviors (Bratiotis & Flowers, 2010; Franks, Lund, Poulton, & Caserta, 2004; Kim, Steketee, & Frost, 2001), and yet squalor is not a key characteristic of hoarding disorder, at least among participants in hoarding research studies (Bratiotis, Sorrentino Schmalisch, & Steketee, 2011; Eckfield, 2011). Therefore, researchers assume that factors other than hoarding behaviors contribute to squalor in some cases and not in others. However, we know little about the factors that predict the presence of squalor and self-neglect in older adults with hoarding behavior. Nor do we know the most effective ways to assist individuals when squalor or self-neglect accompany hoarding behaviors.

Nonetheless, regardless of the terms clinicians and researchers use to describe situations of extreme domestic squalor and self-neglect with or without hoarding behaviors, these situations pose serious and challenging public health problems that threaten not just the individual but also the community in which he lives. Communities are taking note of a problem that certainly will increase in prevalence as the population ages as they search for ways to intervene. For example, in the United States, cities and counties have increasingly viewed hoarding as a subtype of elder self-neglect in order to mobilize public agency resources to address emerging problems (Chapin et al., 2010). It is possible, although we have no research to guide us at this time, that many of the cases for which harm reduction is most appropriate may be hoarding situations accompanied by squalor or self-neglect because these individuals are at considerable risk and present significant public health risks as well.

In addition to neurodegenerative disorders, such as Alzheimer’s disease and frontotemporal dementia, hoarding behavior may be associated with a number of medical conditions and genetic disorders.

Parkinson’s disease (PD) is a degenerative disorder of the central nervous system. Deterioration and death of dopamine-generating cells in the substantia nigra region of the midbrain is thought responsible for the motor symptoms of PD. Movement-related symptoms include shaking, rigidity, slowness of movement and difficulty with walking and gait. Later, cognitive and behavioral problems may arise, with dementia commonly occurring in the advanced stages of the disease and depression (Jankovic, 2008; Shulman, De Jager, & Feany, 2011). In addition, impulsive behaviors, such as pathological gambling, compulsive buying, and compulsive sexual behavior, occur in PD and may be due to the phenomenon of dopamine dysregulation syndrome (Merims & Giladi, 2008; Voon, Potenza, & Thomsen, 2007). Hoarding behavior occurs in PD as well and is probably related to the spectrum of impulsive behaviors in PD (Sullivan et al., 2010). Typically, the onset of hoarding symptoms follows the onset of PD and the age of onset is often much later than for hoarding disorder (Pertusa & Fonseca, 2014).

Huntington’s disease (HtD) is an autosomal-dominant neurodegenerative genetic disorder (Walker, 2007) that affects muscle coordination and leads to cognitive decline (Montoya, Price, Menear, & Lepage, 2006) and behavioral and psychiatric problems (Wagle, Wagle, Markova, & Berrios, 2000). Investigators have identified the presence of obsessive-compulsive symptoms, including saving and collecting behaviors, for people with HtD but believe it unlikely that clinicians will encounter a hoarding syndrome as a prodromal presentation of HtD (Beglinger et al., 2008). Although, hoarding behaviors can occur with HtD, the presence of other clinical features of HtD will likely differentiate HtD-related hoarding behaviors from hoarding disorder (Pertusa & Fonseca, 2014).

In addition to Huntington’s disease, hoarding behaviors can occur with other genetic disorders, including PWS and velocardiofacial (22q11 deletion) syndrome (VCFS). PWS is a rare genetic disorder caused when a subset of genes on the paternal chromosome 15 are missing or unexpressed (15q partial deletion) (Cassidy, Schwartz, Miller, & Driscoll, 2011). Symptoms of PWS include low muscle tone, short stature, incomplete sexual development, cognitive disabilities, problem behaviors, and a chronic feeling of hunger that can lead to food-seeking behaviors, such as foraging and hoarding, and can result in excessive eating and life-threatening obesity (Dykens, Leckman, & Cassidy, 1996; Holm et al., 1993). Velocardiofacial syndrome (VCFS) is a genetic disorder caused by the deletion of a small piece of chromosome 22 (22q11.2 deletion) (Driscoll et al., 1992). Symptoms of VCFS include birth defects (such as congenital heart disease, defects in the palate), learning disabilities, recurrent infections, and psychiatric illnesses, such as schizophrenia, and OCD (Feinstein, Eliez, Blasey, & Reiss, 2002). In one study, hoarding behaviors (which was considered a symptom of OCD in this study) were present in approximately one-third of the VCFS subjects (Gothelf et al., 2004).

Traumatic brain injury or brain lesions that result in damage to the anterior ventromedial prefrontal and cingulate cortices may be implicated in hoarding behavior (Anderson, Damasio, & Damasio, 2005; Cohen, Angladette, Benoit, & Pierrot-Deseilligny, 1999; Hahm, Kang, Cheong, & Na, 2001; Volle, Beato, Levy, & Dubois, 2002).

Anecdotally, many people who have sought help for hoarding behavior in the past left the office of the clinician with a diagnosis of OCD. This is consistent with the view of the majority of OCD experts who agree that hoarding is one of several potentially overlapping dimensions of OCD (Mataix-Cols, Pertusa et al., 2007).

Studies examining the prevalence of hoarding symptoms among those with OCD suggest that the two conditions are often comorbid. The prevalence rate of hoarding symptoms among those with OCD is between 14 and 42 % (Fontenelle, Mendlowicz, Soares, & Versiani, 2004; Frost, Krause, & Steketee, 1996; Rasmussen & Eisen, 1992; Samuels et al., 2002; Sobin et al., 2000). Thus, someone who has OCD is likely also to endorse hoarding symptoms. However, the majority of those with OCD do not have hoarding behaviors (Frost, Steketee, Tolin, & Brown, 2006a, 2006b), further indicating that hoarding symptoms often occur independently from OCD. Furthermore, the prevalence of hoarding behavior among OCD clients is not significantly higher than the prevalence of hoarding behavior among a mixed outpatient group or even controls (Wu & Watson, 2005).

Hoarding symptoms correlate with OCD symptoms and traits such as indecisiveness, perfectionism, responsibility, checking, and doubting in both clinical and nonclinical samples (Frost & Gross, 1993). In addition, although hoarding correlates with checking, washing, obsessing, neutralizing, and ordering symptoms on the obsessive-compulsive inventory-revised (OCI-R) (Foa et al., 2002), the correlation is more modest than the correlation of those symptom domains with one another (Abramowitz, Wheaton, & Storch, 2008; Wu & Watson, 2005).

Additional evidence that hoarding is distinct from OCD comes from factor and cluster analyses of hoarding symptoms. In these analyses, hoarding symptoms consistently emerge as independent from other OC symptoms, with the exception of symmetry or ordering compulsions (Baer, 1994; Calamari, Wiegartz, & Janeck, 1999; Summerfeldt, Richter, Antony, & Swinson, 1999). Consistent with the findings of individual studies, a review of 12 factor-analytic studies of OCD yielded the four consistent factors of symmetry/ordering, hoarding, contamination/cleaning, and obsessions/checking (Mataix-Cols, Rosario-Campos, & Leckman, 2005).

Not only do hoarding symptoms appear to be distinct from other OC symptoms, but also hoarding symptoms do not respond as well to the typical treatments for nonhoarding OC symptoms. Specifically, hoarding symptoms in several studies predict poor response to treatments that are generally effective for OCD, including selective serotonin reuptake inhibitors and cognitive behavioral therapy (Black et al., 1998; Mataix-Cols, Rauch, Manzo, Jenike, & Baer, 1999; Winsberg, Cassic, & Koran, 1999). Furthermore, OCD patients who score high on the hoarding dimension of the Yale Brown Obsessive-Compulsive Scale (Goodman et al., 1989) drop out of treatment prematurely compared to OCD patients with more modest scores on that dimension (Mataix-Cols, Marks, Greist, Kobak, & Baer, 2002). Results such as these suggest that typical treatments for OCD do not target the underlying psychobiological underpinnings of hoarding symptoms. Last, investigators have speculated that neuroanatomical differences may reflect unique psychobiological underpinnings of hoarding. Neuroimaging studies reveal different patterns of brain metabolism between hoarding symptoms and other OCD symptoms (Mataix-Cols et al., 2004; Saxena et al., 2004).

In sum, recent investigations suggest that hoarding is a syndrome that is clinically distinct from OCD (Rachman, Elliott, Shafran, & Radomsky, 2009). Whereas some people with OCD have hoarding symptoms, Abramowitz and colleagues (Abramowitz et al., 2008) liken this relationship to that of substance abuse and post-traumatic stress disorder (PTSD). While many people with PTSD report substance abuse, substance abuse is not a symptom or sign of PTSD.

At times, clinicians will give a diagnosis of OCPD to people presenting with hoarding symptoms, in part, because the DSM-IV TR lists the “inability to discard worn-out or worthless objects even when they have no sentimental value” (American Psychiatric Association, 2000) (p. 673) as one of the criteria for a diagnosis of OCPD. This phrasing does not capture current conceptualizations of clinically significant hoarding problems, however, as most people who hoard assign a great deal of sentimental value to their possessions.

There is evidence that hoarding is not a central diagnostic feature of OCPD. Several studies have failed to find a relationship between measures of hoarding and OCPD (Frost et al., 1996; Frost & Gross, 1993; Frost, Steketee, Williams, & Warren, 2000). For example, Baer (1994) found that high scorers on the symmetry/hoarding factor of OCD were more likely to have comorbid OCPD. This may reflect an association between the obsessive-compulsive need for symmetry and OCPD rather than an association between hoarding and OCPD, per se. In another study, hoarding symptoms more strongly correlated with obsessive-compulsive and avoidant personality disorders than with OCPD (Mataix-Cols, Baer, Rauch, & Jenike, 2000) while another showed the strongest association with dependent and schizotypal personality disorders (Frost, Steketee, Williams, & Warren, 2000) rather than with OCPD. Hoarding symptoms, then, appear to occur with many personality disorders. Furthermore, researchers have proposed that future diagnostic criteria for OCPD not include the hoarding and miserliness criteria because these criteria did not fit well into a factor-analyzed model of relevant diagnostic criteria for OCPD (Hummelen, Wilberg, Pedersen, & Karterud, 2008). For these reasons, while this criterion was retained in the main body of the DSM-5, developers removed it in the alternative model of OCPD that was included in Section III of the DSM-5 (Pertusa & Fonseca, 2014).

A number of psychological disorders include hoarding symptoms: dementia (Greenberg et al., 1990; Hwang et al., 1998), post-traumatic stress disorder (Cromer, Schmidt, & Murphy, 2007; Hartl et al., 2005), attention-deficit/hyperactivity disorder (ADHD) (Grisham et al., 2007; Hartl et al., 2005), brain injury (Eslinger & Damasio, 1985), social phobia (Steketee, Frost, Wincze, Greene, & Douglass, 2000), and alcohol dependence (Samuels et al., 2008). Investigators also found hoarding to co-occur with bipolar II disorder and eating disorders (Fontenelle et al., 2004; Frankenburg, 1984). Therefore, researchers can conceptualize hoarding behavior much like they do depression. Hoarding behavior can accompany almost any other clinical presentation, but remain its own disorder. Several psychological disorders are worth describing further to assist clinicians to differentiate between hoarding disorder and another psychological disorder which they may confuse with hoarding disorder: depression, schizophrenia, autism spectrum disorders, and post-traumatic stress disorder or traumatic life events.

Although 50 % of people with hoarding disorder suffer with a major depressive disorder (Frost, Steketee, & Tolin, 2011), researchers know little regarding the prevalence of hoarding behaviors in people who are depressed. Clinicians may confuse a client with major depression with a client with hoarding disorder if they over focus on the quality of the living spaces and the client’s self-care. A core symptom of major depression is anergia, a condition of lethargy, apathy, poor self-care, and neglect of the immediate environment. A client who is depressed and anergic may not have the energy or the will to take care of herself or her home. She might open a can of soup to warm and drop the can on the floor rather than exert the energy to drop it in the trashcan. She may no longer care about her appearance or the state of her home because she does not care about much of anything. This may lead to clutter and the deterioration of the client’s living space. Careful inquiry regarding the onset of the hoarding symptoms in relationship to the onset of the depressive symptoms may help distinguish hoarding disorder from major depression. If the symptoms of depression predate the onset of hoarding behavior, the client more likely meets criteria for the diagnosis of major depression rather than hoarding disorder. Furthermore, the client’s apathy may extend to her possessions and she may be unconcerned about damaging or discarding the items (Pertusa & Fonseca, 2014).

Studies have estimated the prevalence rates of OCD and obsessive-compulsive symptoms in schizophrenia to be between 8 and 40 % (Poyurovsky et al., 2001; Poyurovsky, Bergman, & Weizman, 2006; Poyurovsky, Fuchs, & Weizman, 1999). Studies suggest that hoarding behavior is not more frequent or more severe in schizophrenia than in the general population (Guillem, Satterthwaite, Pampoulova, & Stip, 2009; Kumbhani, Roth, Kruck, Flashman, & McAllister, 2010). Hoarding behavior, however, may occur secondary to specific hallucinations or delusions. For example, a man who believes that a powerful and malevolent organization is watching and documenting his every move may save any scrap of paper on which he has written. Similarly, a woman who is awaiting word from an alien race may acquire and save newspapers, magazines, photos, or tape radio and television programs to search for clues that the aliens have arrived. Clinicians may differentiate the hoarding behavior associated with schizophrenia from hoarding behavior in hoarding disorder by the presence of a delusional system. That is, the individual will explain his hoarding behavior based on the delusional beliefs he holds.

Similar to major depression, individuals may appear to save items, including waste, because they lack drive or motivation. For example, a 56-year-old man with schizophrenia but with few positive symptoms of the illness, lives in a squalid and highly cluttered apartment because he has little motivation to discard dirty food containers, or used paper tissue. In these cases, clinicians may observe that the client with schizophrenia does not appear to have intense emotional attachments to his possessions and is not likely to resist attempts to assist him to discard items or to clean his residence.

Researchers have noted a high prevalence of hoarding behaviors in people with autism spectrum disorders (Bejerot, 2007; Pertusa et al., 2012; Russell, Mataix-Cols, Anson, & Murphy, 2005). Although further studies are needed, these current studies suggest that people with autism spectrum disorders endorse more severe hoarding behaviors compared to people with OCD and other anxiety disorders, and the presence of hoarding behaviors in people with autism spectrum disorders appears to be unrelated to the presence of comorbid OCD (Pertusa et al., 2012). However, hoarding behaviors for people with autism spectrum disorders can include behaviors related to a number of behaviors specific to autism spectrum disorders, such as collecting items to satisfy special and fixed interests.

Clinicians often view post-traumatic stress disorder (PTSD) or traumatic life events as a precursor to hoarding behaviors. Although people with hoarding disorder appear to have a higher incidence of traumatic life events, rates of comorbid PTSD were no more frequent for people with hoarding disorder than for people without hoarding disorder (Landau et al., 2011). Similarly, investigators reported 7 % (Frost et al., 2011) and 23 % (Hartl et al., 2005) comorbid PTSD in people with hoarding disorder, which suggests that despite experiencing a range of traumatic events, PTSD among people with hoarding disorder is relatively uncommon. However, given that the prevalence of traumatic life events is relatively common in people with hoarding disorder, clinicians may wish to screen for PTSD or traumatic life events in cases where hoarding behavior is the presenting complaint but the individual does not meet full criteria for hoarding disorder.

To summarize, hoarding behaviors often accompany other disorders or conditions. When assessing an individual who has hoarding symptoms, clinicians may wish to cast a wide net to assess for other conditions that are commonly associated with hoarding behaviors. Some of these co-occurring problems or conditions may complicate a harm reduction approach and, for that reason, may require clinicians to target these conditions in the harm reduction plan for the severe hoarding problem. In addition, hoarding behavior that is a secondary rather than a primary feature of a condition, such as psychosis, may improve by treating the primary condition directly.

People with hoarding disorder have great difficulty discarding or parting with their possessions. The prospect of discarding unleashes a flood of catastrophic thoughts. What if I need the item some day? What if I discard the item and need it and cannot find an adequate replacement? What if I discard a piece of information and no longer remember the information when I need to? It’s terrible to waste anything. It’s terrible if someone needs something that I once had and I cannot give the item to the person. The act of discarding is slow and careful as people who hoard deliberate about each possession. They carefully consider each page of the newspaper or reflect on the ways they could use an item.

People who hoard most often have great difficulty discarding “ordinary” possessions, such as newspapers, junk mail, old receipts, notes or lists, magazines, bags, books, boxes, and clothing. The types of possessions people who hoard save does not differ from possessions that people without a hoarding problem save (Frost & Gross, 1993; Winsberg et al., 1999). However, some people who hoard are unable to discard perishable items and items that others would likely describe as waste rather than as a possession, such as nail clippings, used band aides, or their own excrement.

People with hoarding disorder purposefully save possessions and feel very distressed when facing the prospect of parting with them. The accumulation of possessions is not the result of messiness or laziness but rather to the purposeful intention to save and to avoid discarding possessions. Active and purposeful accumulation of possessions distinguishes hoarding disorder from the passive accumulation of items or absence of distress when discarding possessions associated with other psychological conditions, such as major depressive disorder, organic brain disorders, or dementia.

The gradual accumulation of too many possessions, coupled with poor or minimal organizational skills, results in another central criterion for hoarding disorder—clutter. Clutter results when a person is unable to keep up with the task of organizing and storing possessions because of the large number of possessions that come into the home through unbridled compulsive acquisition. Misguided attempts to organize possessions by attempting to keep everything in sight add to the level of clutter in living spaces. Clutter may extend outside the home as the person who hoards fills his home, his car, his garage, and back yard with possessions. In addition, people who hoard may seek to relocate and store possessions in the garages and yards of friends and family members or they may rent one or more storage units, or store possessions at their work site (Saxena & Maidment, 2004).

At times, however, the living space of a person with a hoarding disorder may not be highly cluttered if he has enough space or financial resources to keep the clutter out of the living areas. Someone in an 800 square foot apartment is likely to clutter his living space much sooner than someone living in a 4,000 square foot home with the financial means to rent additional storage space as needed. For example, by the time Betty was 73 years old, she had accumulated so many items that she literally had three houses full of stuff. Her husband managed the level of clutter in the house in which they lived by hauling much of it away to one of their other homes in the vicinity. In this way, Betty was able to lessen her distress because she had the financial means to store her possessions. In cases such as this, the individual would still meet criteria for hoarding disorder because other factors contributed to the absence of clutter in the living space.

People with hoarding disorder experience a clinically significant level of distress or interference caused by the hoarding behaviors. Hoarding is a clinical problem when the clutter or the saving behaviors significantly interfere with the person’s ability to live comfortably and safely within his home or if it affects others’ ability to do so. Many people with hoarding disorder have not been able to sit at their dining table or sleep on their beds for many years. They cannot cook meals, do laundry, or use their showers or toilets because these spaces are filled with clutter, or because their appliances are broken and they are afraid to permit someone into their homes to repair them. Clutter also leads to social isolation and family estrangement. One woman with hoarding first sought treatment for it in her mid-seventies when her adult children refused to allow her grandchildren to sleep at her house because they feared for their children’s safety.

Even if clutter causes a significant amount of interference in a home, the clutter may not distress the resident. For example, every week one client misplaced her checkbook, glasses, or prescription pills in her severely cluttered home. When she had her friends over to have lunch, she had to prepare for days by clearing a corner of the kitchen and a table and chairs so there would be a place to sit. These inconveniences did not distress her. In fact, she had grown accustomed to them. Furthermore, she asserted that her friends accepted her for “who she was.” Many people who hoard take the view that the clutter and its consequences are minor inconveniences. Consequently, they may not feel distressed by their living conditions. Rather, what distress they experience stems primarily from the complaints of others (Rachman et al., 2009) or when they or others attempt to discard or relocate a possession. It is his or her loved ones, neighbors, spouses, or other involved parties who are often the most distressed by the hoarding problem.

The diagnosis of hoarding disorder includes two exclusion criteria that allow clinicians to rule out other conditions that may include hoarding behaviors. As mentioned earlier, hoarding behaviors can occur in a number of medical and psychological conditions. An individual would not meet criteria for hoarding disorder if the hoarding symptoms are better accounted for by the symptoms of a medical or alternative psychological condition.

The diagnosis of hoarding disorder includes two specifiers: excessive acquisition and level of insight. Although 90 % of people who hoard exhibit excessive acquiring (Frost, Tolin, Steketee, Fitch, & Selbo-Bruns, 2009), not all people who hoard excessively acquire items. In most cases, people who hoard leave the house actively to acquire, rather than passively accepting items into the home, such as junk mail or food take-out containers. Active and passive accumulation of items over many years and accompanied by difficulty discarding items results in a gradual accumulation of items in the living space.

People with hoarding disorder present with a range of insight and this likely influences help-seeking behavior and treatment adherence (Tolin, Fitch, Frost, & Steketee, 2010). In hoarding disorder, insight refers to the level or degree the individual is aware of the consequences of the symptoms (e.g., safety for self and others, impairment in day-to-day functioning, or consequences of family members) in addition to hoarding-related beliefs (e.g., abut the importance of possessions). People with hoarding disorder appear to be “blind” to the consequences of the problem despite clear evidence to the contrary.

Over the years, when I have presented on the topic of hoarding to professionals, I often ask for a show of hands of those in the room who know a family member, friend, co-worker, or neighbor who may have a hoarding problem. Nearly every professional in the room, from adult protective service worker to code enforcement officer, raises a hand—sometimes two. It appears that hoarding is indeed a common problem. In a community sample, the prevalence of hoarding was around 4–5 % (Samuels et al., 2008). This may be a low estimate given that those who answered questions in this study may have been reluctant to report the full extent of the problem. In addition, many experts on the topic believe the estimated prevalence of hoarding will increase as visiting nurses, adult protective service workers, and other clinicians involved in the care of older adults discover hoarding situations as part of their duties.

Different studies yield disparate results regarding gender ratios among people who hoard. Part of the discrepancy may relate to examining gender differences in samples of people with OCD versus people in the general population. For example, in a study of patients in a pediatric OCD clinic, over half of the female children had hoarding symptoms compared to 36 % of the male children (Mataix-Cols, Nakatani, Micali, & Heyman, 2008). In other OCD samples, hoarding compulsions seem to be equally prevalent among men (24.6 % of the sample) and women (20.8 %) (Labad et al., 2008). Thus, the prevalence of hoarding symptoms among children and adults may be about the same, or may be more common among females. When we consider gender differences in the general population, however, it looks like more men have hoarding symptoms. In a large community-based sample of 742 participants, 5.6 % of the men agreed that they found it almost impossible to throw away worn-out or worthless possessions compared to only 2.6 % of women (Samuels et al., 2008). In summary, it is not altogether clear who hoards more often—men or women—although the best data may point to men being twice as likely to have hoarding symptoms. The field would benefit from more epidemiological research on hoarding to clarify prevalence rates for men and women, as well other questions about the condition in the general population.

Hoarding behaviors appear to emerge in childhood or early adolescence. In a retrospective study of 51 people who hoard, 60 % of the sample reported onset of hoarding symptoms by age 12, and 80 % reported onset by age 18 (Grisham, Frost, Steketee, Kim, & Hood, 2006). Similarly, in another study, the majority (66 %) of people with hoarding disorder reported that their hoarding behaviors started in childhood, and another 25 % percent reported onset during adolescence or in their early twenties (Frost & Gross, 1993). Thus, hoarding disorder appears to be a condition that begins early and follows a chronic and deteriorating pattern throughout a person’s lifespan, with few people reporting an improvement in their symptoms between onset and the development of severe symptoms (Grisham et al., 2006).

Family factors appear to influence hoarding behavior, as most people who hoard report having a close relative that struggled with the same behaviors. More than three quarters of people with hoarding disorder report having at least one first-degree relative who they believe had hoarding problems (Frost & Gross, 1993). Additional studies have noted a higher prevalence of hoarding among family members of those with hoarding disorder (Pertusa et al., 2008; Samuels et al., 2002). Recent studies lend support for a genetic basis for hoarding with high heritability and a possible linkage of the hoarding phenotypes to specific chromosomes (Mathews et al., 2007; Samuels et al., 2007). Thus, genetic transmission may be one way that people inherit hoarding disorder.

People who hoard often tell others that they hoard because they experienced a period of material deprivation. However, evidence regarding the relationship between material deprivation early in life and development of hoarding symptoms is yet unclear. Frost & Gross (1993) found that there was no difference between people who hoard and nonhoarding participants in response to the question of whether, when younger, there was a period of time when participants had very little money. Although material deprivation does not reliably predict hoarding problems, there is some evidence that significant life events (e.g., marriage, death of a loved one, starting or graduating from school) may be temporally associated with onset of hoarding symptoms for some people who hoard. Grisham et al. (2006) found that 27 of 51 people (55 %) reported a stressful (positive or negative) life event at the onset of hoarding symptoms. Those people who did not report a stressful life event at the time their symptoms began had a significantly earlier age of onset.

Furthermore, traumatic life events are also associated with hoarding symptom severity, suggesting that the experience of trauma may influence the clinical manifestation of hoarding symptoms (Cromer et al., 2007). Additional evidence of the impact of early experiences on hoarding is the finding that hoarding behaviors were three times more likely among participants who reported having a parent with psychiatric symptoms, and four times greater among those who reported either a home break-in or excessive physical discipline during childhood (Samuels et al., 2008). Thus, while information on the etiology of hoarding is still scarce, there is some evidence linking the impact of early negative and traumatic life experiences to onset of hoarding behavior.

There has been little research into the nature of collecting, and less on what reliably differentiates hoarding from collecting. Hoarding may be a less organized pursuit than collecting, wherein they characterize collecting as the accumulation, classification, and meaningful arrangement of possessions (Halperin & Glick, 2003). They suggest that people who hoard are less invested in the individual items and more concerned with the quantity of items. This latter assertion may not accurately reflect that dedicated interest people who hoard demonstrate when they rediscover a possession, whereas the assertion that collectors differ in terms of their level of organization and how they display their possessions may be an apt distinction.

If you needed a swatch of fabric or a skein of yarn, Susan was the person to call. Her friends tease that she has stocked her home better than the local hobby and craft shops. An avid sewer and knitter in her early twenties, Susan began collecting fabric, buttons, beads, and yarn to support her passion. When asked what she liked best about her hobby and collection, Susan shared that no two fabrics or yarns were alike. Thus, not only were the creative possibilities boundless, but also Susan appreciated the “specialness” of each item in her collection. She loved the unique textures of the fabrics and yarns. She reveled in the beauty of beads, turning them this way and that to catch the light or running ribbons through her fingers repeatedly to feel the different bumps and bends in the fabric. At 50 years old, Susan had filled her garage, attic and basement with plastic storage bins filled that contained scraps from projects, unopened bags of beads, and yarns that she bought over 20 years ago. She no longer remembers what she has and has trouble finding an item to use, but each time she takes down a storage bin from a shelf and opens it, she delights in what she finds and nods her head as if to say, “I am so glad I kept this.” She has started to stack bins in her living room because she is out of storage space. She has not worked on a project in many years, but continues to collect supplies in case she ever begins quilting again or in case her local elementary school asks to use some of her supplies for an art class.

Deborah wanted to clean and de-clutter her home, but worried she would forget much of her life or the lives of her children if she did not have something tangible to help her remember. When going through a large pile of ATM receipts from more than 5 years ago, Deborah became tearful as she thought about what she might have been doing with her children on the date of the receipt, and how she and her children likely spent the withdrawn money. She reasoned, “Since this receipt is from June 23, 1999 for $60, I bet I spent it the day I took the kids to the local amusement park. They were on break from school by then.” She would continue, remembering past trips to the park with her children and how good it felt to spend time with them. As she recalled these pleasant and meaningful memories, the ATM receipt became increasingly valuable to her. In addition to the large quantities of paper items in her home, Deborah loved stuffed animals, dolls, and other trinkets that had a “special sweetness” or charm that was irresistible to her. When asked why she purchased a particular stuffed dog, she exclaimed, “Look at his face and his sad, beautiful eyes! How could I leave him in the store with that face?”

Carol loved her job as a librarian. She received an advanced degree in library information science from a prestigious university. She worked for the past 10 years at her town’s public library and enjoyed several benefits associated with her job. The favorite benefit, by far, was that she could take home books that the staff had culled from the library’s holdings. Her co-workers joked, “Carol, you’ve never met a book you didn’t like,” and this was true. Carol carried home books by the armload, even on the most arcane topics, proclaiming, “I bet I know someone who would love to know more about that topic.” She brought home books on inchworms and howler monkeys, books on Russian space travel, books on music theory or auto mechanics. Her basement resembled the town library, but without the shelves. She had piled books 12 rows thick from the wall to the center of the basement floor and 8–10 layers high. She was excited and animated when she described how her books—and knowledge in general—created “intersections between people.” She explained that when she meets someone, she inquires about her interests, and then she searches through her piles of books for one that her new friend might like. She then places the books in her car so that she can give these treasures to the individual next time she sees her. As a result, she had filled her car with books so that there was only room for her to drive and books tumbled down on her with each stop and turn.

Carol knew that much of the information in the books that she saved was available to her online if she wanted to look for it there. She was familiar with search engines and online encyclopedias and even had a computer at home that she occasionally used. However, Carol favored printed information that she could store in her house. She reasoned, “With a book, you have the information available to you if you ever need it. This book on inchworms for example has a wealth of information in it. When I see it, the book reminds me that inchworms are very interesting creatures. However, I would never search online anything about inchworms because I wouldn’t think to do it. Without this book, information about inchworms would be lost to me forever.”

Military memorabilia fascinates Alan. His father served in World War II and passed down to his son a true passion for the United States Army and for the military life in general. Alan had turned his garage into a small, cramped museum. He owned mounts and medals from over 50 countries. Bits and pieces of uniforms, rubber boots and steel helmets, littered the garage floor. Mannequins he had found in a dumpster behind a department store that he had dressed in authentic uniforms from each of the twenty-first century major American Wars lined one wall. For the past 10 years, he has purchased box after box of garb, trinkets, and equipment from army-navy surplus stores, internet auction sites, and through his association with a local Orders and Medals Society. He spends a great deal of time online with other people interested in military antiques but seldom had people over to view his collection. When a close friend did visit, however, Alan enthusiastically described the history of many of the rare and unusual pieces of his collection. His neighbors frequently complained to county officials about the large antiques that littered his front lawn, including old wheel and axle sets and water buckets. Alan was only 57 years old and his family worried that his collection would continue to grow until there was no living space left. When he and a professional organizer sorted through his possessions, they uncovered scores of un-cashed checks from people who had purchased antiques from him. The professional organizer joked with Alan that if Northern California ever went to war, the first stop soldiers would make would be his garage to gear up. Alan did not find this amusing and in a couple of weeks stopped working with the organizer.

Like many people, Kathy loved a bargain. Unlike most people, however, she could not pass up a bargain even when she had 10 or 20 of the same item. Over the years, Kathy’s garage began to resemble a bomb shelter. Shelves in Kathy’s home held canned foods, pallets of water bottles, reams of toilet paper, box after box of facial tissue, large packages of health and beauty supplies, and cases of batteries. Kathy had over 100 bottles of unopened shampoo and bragged about how little she had paid for them. When Kathy traveled, she brought home all the shampoos, soaps, and shower caps from the hotel rooms. When she moved from an apartment several years ago, she recalled saving each of the nails that she pulled from the walls where her pictures had hung, in case she needed them again in the future. Every item had a potential use and she would not waste it, not even an old bent nail.

From an early age, Gina took pride that she was always prepared. In high school, her girlfriends came to her if they needed a mirror, an aspirin, a nail file, or a safety pin. As long as she can remember, she bought extra-large purses that could carry not only her wallet, but also a potpourri of medicines, mints, Kleenex, pens, Band-Aids, notepads, stamps, quarters, safety pins, business cards, a water bottle, and hard candies. Her motto was, “Preparedness is next to Godliness.” She explained that throughout her life, she had learned the value of being prepared when someone asked her for an item, and naturally, she had it. Ironically, while Gina had prepared herself well for small mishaps, such as a small cut or a broken fingernail, she was unprepared to manage the predictable day-to-day demands on her time and resources, such as paying bills, preparing meals, or shopping for family birthdays. She was aware of this discrepancy but explained, “I focus my energies on what could happen and not on what is happening.”

Walking into Edward’s backyard was like walking into the local big-box home supply store. Along the fence, he had stored hundreds of wood planks of different lengths and widths. He had lined the length of his driveway with cardboard box after cardboard box filled with ceramic tiles and bags of grout. He had filled the back room of his house with several power saws and had built shelves to hold mason jars filled with nails, screws, washers, and every piece of hardware imaginable. Edward worked as a builder and contractor for 30 years and had been remodeling his home for the past 10 years. He planned to move from his current home into the remodeled one once he completed the work. At the same time, he debated whether it made more sense for him to stay in his current house and sell this second home. The thought of moving all his possessions overwhelmed him, in part, because of the enormity of the task but also because he did not know where in the new home he would put all his possessions. In addition, Edward could not imagine discarding any of the building materials, hardware, and tools that he had amassed. He knew his possessions were valuable and planned to sell much of his inventory online, but it was one of those tasks he never seemed to find time to begin.

To Edith, if she did not write down a thought or idea on a piece of paper and kept it, the thought or idea was lost to her forever. Although Edith’s memory appeared to be fine, her belief that she had a poor memory created a number of problems for her. For one, because she believed her memory was poor, she recorded and saved most of the information that came her way on any given day. The result was that Edith’s house looked as if someone had emptied the contents of several large filing cabinets into the center of each room. Because Edith doubted her memory, she carried notepads and pencils in her purse to jot down information she heard on public radio while driving. Pieces of paper dating back several years covered the front seat of her car. She also kept information about festivals, free events, or other happenings that were interesting to her. Her motive was virtuous. She believed that she was saving the information for friends and acquaintances and someday they might want the information she had so carefully collected. Edith had great trouble discriminating the relative value of information because to Edith each bit of information was unique and irreplaceable. Compounding her problem was Edith’s belief that information never became outdated. As a result, she kept information long past its expiration date, in a sense. For example, she kept a notice about a museum opening that happened 2 years ago. Edith reasoned that although the information was not current, it might at least point someone in the right direction if he wanted to find current information on the topic.

Kevin knew that his two kids might never want to look through their grade-school art projects when they were adults, but he was committed to keeping every single one for them, just in case. The six boxes under the coffee table in the family room contained several years of science and art projects, as well as various trophies, badges, and other accolades that his children had won. His children, who were now 9 years and 12 years old, had worn many Halloween costumes and he had kept all the costumes, along with photographs of the children wearing them because, “When I see the costumes, it’s like the memory floods over me.” His wife, Karen, who had created many of those costumes, begged Kevin to donate them to Goodwill in order to free up additional storage space in the home. Kevin, however, refused. Kevin was a good father and good fathers honored and preserved the special times they had with their children. As a result, anything related to the day-to-day lives of his children was special—even sacred—and he could never let go of it, not even the crushed and misshapen painted toilet roll cylinders his son had made in preschool.

The first factor in the cognitive-behavioral model of hoarding behavior pertains to deficits in information processing, which include difficulties with attention, memory, categorization, and decision-making. These difficulties are interrelated and profoundly influence hoarding behavior. For example, problems with attention make it difficult for people who hoard to stay focused on the myriad of tasks associated with organizing and decluttering an environment efficiently. ADHD may be highly comorbid with hoarding (Grisham et al., 2007; Hartl et al., 2005) and may complicate the treatment of hoarding disorder if the inattention is not treated and managed as well.