Obsessive-Compulsive and Related Disorders

Chapter 9
Obsessive-Compulsive and Related Disorders


Sandra M. Neer and Katie A. Ragsdale


Obsessive-Compulsive and Related Disorders is a new category in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5; American Psychiatric Association [APA], 2013) and includes obsessive-compulsive disorder (OCD), body dysmorphic disorder (BDD), hoarding disorder (HD), trichotillomania (TTM), and excoriation (skin-picking) disorder (ED). The new DSM-5 category includes disorders previously categorized elsewhere within the DSM-IV-TR (APA, 2000) (e.g., anxiety disorders [OCD], somatoform disorders [BDD], and impulse-control disorders not elsewhere classified [TTM]), as well as two new diagnoses (HD and ED). The disorders were reclassified within this new category to reflect their diagnostic and clinical relatedness (APA, 2013).


Diagnostically, OCD is characterized by obsessions and/or compulsions that consume more than 1 hour per day or cause clinically significant distress or impairment (APA, 2013). Obsessions include recurrent and persistent thoughts, urges, or images (e.g., thoughts of contamination or urges to kill someone) of an intrusive or unwanted nature, which individuals attempt to suppress, ignore, or neutralize (e.g., by performing a compulsion). Compulsions are repetitive behaviors or mental acts (e.g., counting or washing) individuals engage in to prevent or reduce anxiety or distress. Compulsions do not need to be logically connected to the obsessions they are attempting to neutralize, although they often are.


BDD is defined by a preoccupation with perceived physical defects or flaws that, at some point during the course of the disorder, result in repetitive behaviors (e.g., mirror checking) or mental acts (e.g., appearance comparisons) (APA, 2013). Preoccupation can occur with any part of the body (e.g., hair, face shape, or nose) but is most commonly associated with the skin (e.g., wrinkles or scars). Although the perceived defects or flaws cause clinically significant distress or impairment to the individual, they appear minor or unrecognizable to others. Individuals who are preoccupied with body build, believing that the body is too small or insufficiently muscular, would meet criteria for the specification of BDD with muscle dysmorphia. Additionally, clinicians can specify whether an individual’s level of insight is good, fair, poor, or absent. In a case where an individual is completely convinced of their defect, absent insight/delusional beliefs may be specified.


HD, a new diagnosis of the DSM-5, reflects persistent difficulty parting with possessions to the point that it causes clinically significant distress or impairment (APA, 2013). Difficulty discarding an item is unrelated to the item’s actual value; rather, it is related to both the distress associated with discarding the item and a perceived need to save it. As a result, accumulation of possessions causes congestion and clutter in living areas, which substantially compromises their intended uses. In addition, individuals who excessively acquire additional possessions which are not needed or for which there is no room would meet criteria for the specification of HD with excessive acquisition.


TTM (hair-pulling disorder) is defined by recurrent hair pulling that results in hair loss. Although hair pulling typically results in visible hair loss, individuals who widely pull hair from various body regions may not evidence this clinical marker (APA, 2013). The scalp, eyelids, and eyebrows are the most common sites; however, hair pulling may occur at any region of the body where hair grows. In addition to hair pulling, individuals suffering from TTM repeatedly attempt to decrease or stop hair pulling, and endorse significant associated distress or impairment.


ED (skin picking), also a new disorder to the DSM-5, is characterized by recurrent skin picking which results in skin lesions (APA, 2013). Skin picking commonly occurs on the face, arms, and hands; however, individuals may pick various body regions (APA, 2013). Although individuals typically use fingernails to pick, other objects (e.g., tweezers) and techniques (e.g., squeezing or rubbing) may be used. Individuals may pick at a variety of sites including healthy skin, scabs, or skin irregularities, and repeatedly attempt to decrease or stop skin picking. As with all other psychiatric disorders, individuals must experience clinically significant distress or impairment to meet diagnostic criteria.


Clinical Features


OCD is a clinically heterogeneous disorder with various presentations of obsessions and/or compulsions. Although individuals do not need to endorse both obsessions and compulsions to meet diagnostic criteria (APA, 2013), 96% of outpatients with OCD report experiencing both, whereas 2% endorse predominant obsessions and 2% report predominant compulsions (Foa & Kozak, 1995). Among this large sample of individuals from the DSM-IV field trials, the most common obsession reported was contamination (37.8%), followed by fear of harming self or others (23.6%) and symmetry (10%). The most common compulsions reported were checking (28.2%) and cleaning/washing (26.6%). Other obsessions included somatic, religious, and sexual obsessions, whereas other compulsions included repeating, mental rituals, ordering, and counting.


A meta-analysis of factor analytic studies of OCD symptom categories revealed four factors, which explained nearly 80% of the variance in 17 studies of adults with OCD (Bloch, Landeros-Weisenberger, Rosario, Pittenger, & Leckman, 2008). The four factors included symmetry (symmetry obsessions and repeating, counting, and ordering compulsions), cleaning (contamination obsessions and cleaning compulsions), forbidden thoughts (aggressive, religious, and sexual obsessions), and hoarding (hoarding obsessions and compulsions). Often, obsessions and compulsions are functionally related (e.g., contamination fears accompanied by cleaning rituals or self-doubt and dread accompanied by repetitive checking; Turner & Beidel, 1988). For instance, strong associations exist between some similar obsessions and compulsions (e.g., contamination obsessions and cleaning compulsions), whereas others are less specific (e.g., checking compulsions are related to a variety of obsessions) (Bloch et al., 2008).


OCD is a debilitating disorder with significant functional impairment and reduced quality of life (Norberg, Calamari, Cohen, & Riemann, 2008). In fact, a recent review found that quality of life in OCD is significantly lower than quality of life in community controls and individuals with other psychiatric and medical disorders (Macy et al., 2013). Unfortunately, despite the associated impairment and distress, few individuals with the disorder initiate treatment (Levy, McLean, Yadin, & Foa, 2013).


Clinically, BDD is marked by preoccupation with physical appearance that results in repetitive behavioral or mental acts. On average, preoccupation is focused on five to seven areas of the body (Phillips, Menard, Fay, & Weisberg, 2005). Although the clinical presentation in men and women is more similar than different, implicated body regions differ significantly (Phillips, Menard, & Fay, 2006). Men are more likely to be preoccupied with body build, genitals, and hair thinning or balding, whereas women are more likely to be preoccupied with a wider variety of body areas (i.e., skin, stomach, weight, breasts, buttocks, thighs, legs, hips, toes, and excessive body or facial hair). Repetitive or safety behaviors in response to body preoccupation may include comparison to others, camouflaging (i.e., using body posture or position, clothes, and makeup, among others, to hide the perceived defect), mirror checking, grooming, reassurance seeking, dieting, and tanning (Phillips et al., 2005).


Individuals with BDD endorse high rates of both suicidal ideation and suicide attempts due to appearance concerns (Rief, Buhlmann, Wilhelm, Borkenhagen, & Brähler, 2006). For instance, in a sample of 200 individuals with BDD, 81.3% of treated subjects and 71.2% of untreated subjects endorsed suicidal ideation, and over a quarter of all subjects had attempted suicide (Phillips et al., 2005). Further, individuals with the disorder are more likely to be divorced, unmarried, unemployed, and have lower incomes than individuals without the disorder (Rief et al., 2006) and may be housebound, miss work and school, drop out of school, and receive disability (Phillips et al., 2005). Despite the associated distress and impairment, few individuals with BDD disclose their body image concerns to clinicians, most often due to feelings of embarrassment or fears of being negatively evaluated (Conroy et al., 2008). Instead, many individuals with the disorder receive nonpsychiatric treatment (i.e., dermatology and cosmetic surgery) (Phillips et al., 2005).


The typical clinical presentation of HD involves an individual who has significant difficulty parting with possessions and associated distress and impairment. Over two-thirds of individuals with the disorder may also exhibit excessive acquisition of items, which has been found to be a clinical predictor of distress and/or impairment (Timpano et al., 2011). Individuals with the disorder most frequently accumulate items through purchase (64.4%) and obtaining free things (53.4%); however, a subsample of those who engage in excessive acquisition may also steal (25.3%). Clinically significant hoarding may lead to work impairment, eviction from the home, and/or removal of others from the home, and is a significant public health burden (Tolin, Frost, Steketee, Gray, & Fitch, 2008).


The hallmark symptom of TTM is clinically significant hair pulling. Individuals usually pull hair from multiple sites, most frequently being the scalp, followed by eyelashes, eyebrows, and pubic hair (Flessner, Woods, Franklin, Keuthen, & Piacentini, 2009). Although it is not necessary for diagnosis, many adults with the disorder report an urge, need, or drive to pull hair, as well as a sense of gratification or relief during or after pulling (Lochner et al., 2012). Most individuals pull out single hairs (68%); however, some may pull out clumps (5%), or a combination of single hairs and clumps (27%) (Christenson, MacKenzie, & Mitchell, 1991). Additionally, individuals may target specific types of hair based on thickness, texture, or color and may manipulate hair after it is pulled (e.g., suck on hairs or scrape off roots) (Walsh & McDougle, 2001). Finally, individuals with TTM may express associated negative affective states, including feeling unattractive (87%), secretiveness (83%), shame (75%), irritability (71%), low self-esteem (77%), and depressed mood (81%) (Stemberger, Thomas, Mansueto, & Carter, 2000).


ED describes clinically significant picking of the skin that results in skin lesions. An examination of 60 individuals with pathologic skin picking suggests that the disorder is time-consuming and associated with various complications (Odlaug & Grant, 2008). Results of this study also suggest that individuals often begin picking in response to triggers, such as feel (55%) or sight (26.7%) of the skin, boredom/downtime (25%), and stress (20%). The face and head (60%) are the most common sights for picking, followed by the legs and feet (33.3%), arms (30%), torso (23.3%), and hands and fingers (21.7%). Most individuals (68.8%) pick from multiple sites of the body, often switching areas in order for other sites to heal. In fact, 35% of this sample experienced infections requiring antibiotics as a result of skin picking.


Diagnostic Considerations


The National Comorbidity Survey Replication (NCS-R; Kessler et al., 2004) found that 90% of individuals with a lifetime diagnosis of OCD met criteria for an additional DSM-IV disorder (Ruscio, Stein, Chiu, & Kessler, 2010). The most common comorbid disorders were anxiety disorders (75.8%), followed by mood disorders (63.3%), impulse-control disorders (55.9%), and finally substance use disorders (38.6%). Within anxiety disorders, the highest comorbidity rates were found for lifetime social phobia (43.5%), specific phobia (42.7%), and separation anxiety disorder (37.1%); whereas major depressive disorder (40.7%) was the most frequent comorbid mood disorder. Another study that examined a wider variety of DSM-IV disorders also found high rates of lifetime anxiety and depression comorbidity, as well as high rates of lifetime comorbid obsessive-compulsive personality disorder (24.7%) in individuals with OCD (Pinto, Mancebo, Eisen, Pagano, & Rasmussen, 2006).


In a sample of 200 individuals with BDD, lifetime comorbidity was compared in treated and untreated individuals (Phillips et al., 2005). Comorbidity rates were highest for mood (88.1% in treated individuals and 75.8% in untreated individuals), anxiety (73.1% and 62.1%, respectively), substance use (50.0% and 43.9%, respectively), and personality disorders (47.9% and 39%, respectively). The highest rate of comorbidity for both samples was major depression (75.4% and 72.7%, respectively); however, rates were relatively high for social phobia (40.3% and 34.8%, respectively) and avoidant personality disorder (26.9% and 22.0%, respectively), which are likely related to appearance concerns associated with BDD.


Literature on the comorbidity rates of HD is sparse, likely due to its introduction as a stand-alone disorder in the DSM-5. However, one recent study did examine current comorbidity of HD (defined by the then-proposed DSM-5 criteria) in 217 individuals with the diagnosis (Frost, Steketee, & Tolin, 2011). Major depression was the most common comorbid mood disorder (50.7%); however, comorbidity rates were also high for attention-deficit/hyperactivity disorder inattentive type (27.8%), generalized anxiety disorder (24.4%), social phobia (23.5%), and OCD (18%).


Similarly, research examining comorbidities of TTM is limited. A recent review suggests mood, anxiety, and substance use disorders are the most commonly identified comorbidities (Duke, Keeley, Geffken, & Storch, 2010). In addition, TTM is related to skin-picking disorder (Snorrason, Belleau, Woods, 2012), which is discussed in more detail next.


Although no literature exists at this time that examines comorbidities of DSM-5 ED, earlier studies examining pathologic skin picking do exist. In one study, comorbidity was examined in a small sample (n = 60) of individuals who engaged in pathologic skin picking, defined similarly to the DSM-5 criteria (with the exception of inclusion of preoccupation, tension, and relief criteria). Results found that 38.3% of individuals met current criteria for an additional DSM-IV disorder, whereas 56.7% met lifetime criteria for another disorder (Odlaug & Grant, 2008). Specifically, 36.7% of individuals met current criteria for TTM (with a similar rate for lifetime diagnosis [38.3%]), 15.0% met criteria for current OCD (16.7% for lifetime), and 15.0% met current criteria for major depressive disorder (31.7% for lifetime). Indeed, the comorbidity of TTM and skin-picking disorder appears to be high, with an average of 20.8% of TTM outpatient samples endorsing skin picking, and an average of 15.5% of skin-picking disorder outpatient samples endorsing TTM, indicating relatedness between the two disorders (Snorrason et al., 2012).


Epidemiology


Due to the recent advent of the DSM-5, current epidemiological studies reflect diagnoses largely based on DSM-IV-TR criteria. Diagnostic changes introduced in the DSM-5, as well as inclusion of new disorders, will likely generate new research that may elucidate changes in prevalence rates reflective of new diagnostic criteria. Thus, epidemiological data reflected here are based on DSM-IV-TR criteria and in samples of U.S. adults, unless otherwise noted.


Although over one-fourth of individuals report experiencing obsessions or compulsions at some point in their lives, meeting diagnostic criteria for OCD occurs in a much smaller percentage of individuals (Ruscio et al., 2010). Specifically, the 12-month prevalence rate of OCD is 1.2% and the lifetime prevalence rate is 2.3%. As a result, OCD is a relatively rare disorder.


In a nationally representative study, the point prevalence of BDD was 2.4% (Koran, Abujaoude, Large, & Serpe, 2008); however, rates vary widely depending on the setting. In one study, 1.8% of outpatient adults met criteria for BDD (van der Meer et al., 2012), whereas rates in inpatient samples range from 13.1% to 16% (Conroy et al., 2008; Grant, Kim, & Crow, 2001).


Using the DSM-IV hoarding criterion of obsessive-compulsive personality disorder (i.e., being “unable to discard worn-out or worthless objects even when they have no sentimental value”) (APA, 1994), the weighted community prevalence was 5.3% (Samuels et al., 2008). Similarly, in a large German community sample, 5.8% of individuals endorsed current hoarding according to (then proposed) DSM-V criteria (Timpano et al., 2011).


In a community sample, 0.6% of individuals met DSM-IV-TR criteria for TTM; however, the prevalence increased to 1.2% when the prior diagnostic criteria of building tension or release were ignored (Duke, Bodzin, Tavares, Geffken, & Storch, 2009), suggesting that the DSM-5 criteria may be less restrictive and produce larger prevalence rates. Among a psychiatric inpatient sample, the point prevalence of TTM was 3.4% and the lifetime prevalence was 4.4% (Grant, Levine, Kim, & Potenza, 2005). Interestingly, a similar rate of TTM (3.9%) was found for a sample of college students; however, the latter rate was based on a modified self-report measure of the clinical interview administered to the inpatient sample (Odlaug & Grant, 2010).


Although ED was not an official diagnosis within the DSM-IV-TR (APA, 2000), prevalence rates based on various diagnostic criteria do exist. For instance, in non-clinical community samples, 1.4% to 5.4% of individuals endorsed clinically significant skin picking with associated distress or impairment (Hayes, Storch, & Berlanga, 2009). In a recent study examining prevalence based on (then proposed) DSM-5 criteria, 4.2% of college students met diagnostic criteria for ED (Odlaug et al., 2013).


Psychological and Biological Assessment


Various clinician-administered measures for the assessment of OCD exist. For instance, the Anxiety Disorders Interview Schedule for DSM-IV (ADIS-IV; Brown, DiNardo, & Barlow, 1994) and the Structured Clinical Interview for DSM-IV-TR Axis I Disorders (SCID-CV; First, Spitzer, Gibbon, & Williams, 1996) are semistructured diagnostic interviews that assess for OCD and other disorders. Additionally, the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS; Goodman et al., 1989a; Goodman et al., 1989b) is considered the “gold standard” for assessing OCD symptom severity and now includes a revised second edition (Y-BOCS-II; Storch, Rasmussen, et al., 2010). The Y-BOCS-II is a semi-structured, clinician-administered measure that assesses for the frequency and severity of OCD symptoms over the past week, with good to excellent psychometric properties (Storch, Larson, et al., 2010; Storch, Rasmussen, et al., 2010).


Although OCD is typically assessed using semi-structured clinical interviews, various self-report measures with established reliability and validity exist, including the Y-BOCS-Self Report (Baer, Brown-Beasley, Sorce, & Henriques, 1993; Steketee, Frost, & Bogart, 1996) and Obsessive-Compulsive Inventory (OCI; Foa et al., 2002). Finally, behavioral avoidance tests (BATs), or observational tasks in which individuals are exposed to feared stimuli while rating their distress, have recently been used to assess OCD (Grabill et al., 2008). Specifically, BATs are often administered before treatment to assess the severity of avoidance and distress, and after treatment to assess functional change. Although BATs provide additional clinical information, they are generally considered an adjunct to traditional clinical interviewing, providing particularly helpful information for development of exposure hierarchies. For recent comprehensive reviews of assessment measures for OCD, see Benito and Storch (2011) and Grabill et al. (2008).


Although the SCID-CV (First et al., 1996) screens for BDD, more thorough assessments are needed for diagnosis. For example, the BDD Examination (BDDE; Rosen & Reiter, 1996), a 34-item semi-structured clinical interview, is designed specifically to diagnosis BDD. The BDDE has acceptable reliability and validity, and measures not only the various aspects of preoccupation, but also the level of conviction the individual holds regarding the perceived defect (Cororve & Gleaves, 2001). In addition, the Y-BOCS (Goodman et al., 1989a; Goodman et al., 1989b) was modified for the assessment of BDD (Y-BOCS-BDD; Phillips et al., 1997); however, the measure has been criticized for a narrow focus of obsessive compulsive type symptomatology (Rosen & Reiter, 1996).


The majority of current measures that assess for hoarding are based on DSM-IV-TR criteria (APA, 2000), which conceptualized hoarding as a symptom of OCD or a criterion of obsessive-compulsive personality disorder (Frost, Steketee, & Tolin, 2012). Although hoarding subscales exist on some measures of OCD, more recent measures designed specifically for hoarding have been created and may more accurately assess the diagnostic criteria of the disorder. For instance, the Hoarding Rating Scale-Interview (HRS-I; Tolin, Frost, & Steketee, 2010) is a five-item semi-structured clinical interview used to assess compulsive hoarding and related impairment and distress. The HRS-I exhibits excellent reliability, is sensitive to treatment changes, and can distinguish individuals with hoarding from both OCD patients without hoarding and community controls (Tolin et al., 2010). Additionally, the Saving Inventory–Revised (SI-R; Frost, Steketee, & Grisham, 2004) is a 23-item self-report measure that assesses for clutter, difficulty discarding, and excessive acquisition, which exhibits appropriate reliability and validity. For more comprehensive reviews of assessment of hoarding, see Frost et al. (2012) and Frost and Hristova (2011).


Although no gold standard assessment for TTM exists, there are some measures designed to assess for the disorder (Duke et al., 2010). Measures with acceptable psychometric properties include the Massachusetts General Hospital Hairpulling Scale (MGH-HPS; Keuthen et al., 1995; O’Sullivan et al., 1995), a seven-item self-report scale, and the Milwaukee Inventory for Subtypes of Trichotillomania-Adult Version (MIST-A; Flessner, Woods, Franklin, Cashin, & Keuthen, 2008), a 15-item scale that provides two distinct scale scores (i.e., automatic pulling and focused pulling scores).


There does not appear to be an assessment measure yet developed for the DSM-5 diagnosis of ED; however, some measures do assess for factors related to earlier conceptualizations of skin picking. For instance, the Skin Picking Scale (SPS; Keuthen et al., 2001) is a six-item self-report measure modeled after the original Y-BOCS (Goodman et al., 1989a; Goodman et al., 1989b); however, the measure only assesses for severity of skin picking. Further, similar to the MIST-A (Flessner et al., 2008), the Milwaukee Inventory for the Dimensions of Adult Skin Picking (MIDAS; Walther, Flessner, Conelea, & Woods, 2009) is a reliable and valid assessment of automatic and focused skin picking for individuals who engage in the behavior. Even so, assessment of ED is currently lacking due to the recent advent of the disorder in the latest DSM-5. Clinical interviews or self-report measures that assess for the presence of DSM-5 criteria are of particular need.


Etiological Considerations


Behavioral and Molecular Genetics


OCD has a complex etiology involving both genetic and environmental factors. Evidence from family, twin, and segregation studies shows that heredity plays a major role in the etiology of OCD. In a meta-analytic study, Hettema, Neale, and Kendler (2001) found an average prevalence rate of 8.2% for first-degree relatives of OCD probands compared to 2% in comparison relatives, suggesting heritability. Twin studies of OCD patients also support the presence of significant genetic influence, with estimates of 45% to 65% in children, and 27% to 47% in adults (Jonnal, Gardner, Prescott, & Kendler, 2000). In a large twin study examining heritability of dimensions of OCD, including rumination, contamination, and checking, genetic factors accounted for 36% of the variance for an overall factor of OCD symptoms (van Groothest, Boomsma, Hettema, & Kendler, 2008). The remaining 64% was explained by environmental factors. Only the contamination dimension appeared to be influenced by specific genes and to be an independent dimension.


In another study of OCD symptom dimensions, five major symptom dimensions (checking, hoarding, obsessing, ordering, and washing) were analyzed in a sample of female twins (Iervolino, Rijsdijk, Cherkas, Fullana, & Mataix-Cols, 2011). The authors concluded that no single underlying factor could explain the heterogeneity of OCD. However, the majority of the genetic variance was due to shared genetic factors (62.5%–100%), whereas the nonshared environmental variance was due to dimension-specific factors (Iervolino et al., 2011). In this study, the hoarding dimension had the lowest loading on the common factor and was more influenced by specific genetic effects (54.5%). Future research is needed to help identify specific genetic and environmental factors underlying the dimensions of this heterogeneous disorder.


The specific genetic markers for OCD are largely unknown; however, genome-wide linkage studies that attempt to identify regions that may contain vulnerability genes have been conducted in patients with OCD. Early studies were conducted with small sample sizes and produced mixed results. Taken together, however, these early studies suggest that regions containing chromosome 9 may be of particular importance (Hanna et al., 2002; Shugart et al., 2006; Willour et al., 2004). Although these results are far from definitive, it is interesting to note that several studies have reported an association between OCD and a glutamate transporter gene (SLC1A1), which is located in the area of chromosome 9p (Chakrabarty, Bhattacharyya, Christopher, & Khanna, 2005; Ting & Feng, 2008; Rotge et al., 2010). More recently, however, Mathews and colleagues (2012) conducted a genome-wide linkage analysis using 33 families that had two or more individuals with childhood-onset OCD. Authors identified five areas of interest on chromosomes, with the strongest result on chromosome 1p36. Future studies are needed to replicate this genomic area of interest.


The etiology of BDD is also complex; however, extant research suggests that heritability is an important part of the variance of BDD etiology. A family study investigating the relationship between OCD and possible spectrum disorders revealed that 8% of individuals with BDD have a first-degree relative with a lifetime diagnosis of BDD, which is 3 to 8 times greater than the prevalence in the general population (Bienvenu et al., 2000). Interestingly, 7% of patients with BDD also have a first-degree relative with OCD (Phillips, Gunderson, Mallya, McElroy, & Carter, 1998), and first-degree relatives of OCD patients have 6 times the lifetime prevalence of BDD compared to controls. Taken together, these studies suggest a shared heritability between BDD and OCD.


A recent twin study of BDD revealed that genetic factors accounted for 44% of the variance in dysmorphic concerns, whereas nonshared environmental factors accounted for the remaining variance (Monzani et al., 2012). Although there is limited research regarding specific genetic markers for BDD, one candidate gene study found association for GABA (A)-gamma-2 (5q31.1-q33.2) with the 1 (A) allele occurring more frequently in BDD subjects than controls (Phillips & Kaye, 2007). The GABA (A) receptor-y2 gene was also associated with BDD, but not OCD patients, in a subsequent genetic investigation (Richter et al., 2009).


Information regarding the etiology of HD is primarily derived from research on patients with OCD who have been divided into hoarding or nonhoarding subgroups. Within this framework, hoarding has been shown to have a strong familial association (Pertusa, Fullana, Singh, Menchon, & Mataix-Cols, 2008). In a study of monozygotic and dizygotic twins from the UK twin registry, “caseness” of hoarding was determined by completion of the Hoarding Rating Scale–Self Report (HRS-SR), with 2.3% of the sample reporting symptoms severe enough to be included (Iervolino et al., 2009). The authors found that heritability of hoarding in female twins was associated with both genetic (50%) and nonshared environmental factors (as well as measurement error). Shared environmental factors did not contribute to the liability. It is interesting to add that a significantly higher rate of severe hoarding, as well as any hoarding symptoms (compared to no symptoms), was observed for male twins, compared to female twins.


Given the recent inclusion of hoarding as a diagnostic category, there is little research in the area of genetic etiology of HD. Using data from a large collaborative genetics study of OCD, Samuels and colleagues (2007) found significant linkage of compulsive hoarding to Chromosome 14 in families with OCD. These investigators also found that hoarding and indecision were more prevalent in relatives of hoarding than nonhoarding OCD patients. Future research that focuses on HD as a separate diagnostic entity may help to increase understanding of etiological factors.


The etiology of TTM for any particular patient is most likely an interaction between biological, psychological, and social factors (Diefenbach, Reitman, & Williamson, 2000). Early genetic research indicates that hair-pulling behavior occurs at increased rates (5%–8%) in family members of TTM probands relative to normal controls (Christenson, Mackenzie, & Reeve, 1992; Lenane et al., 1992). Heritability has also been suggested by results of a twin study in which concordance rate for TTM (as defined by DSM-IV-TR criteria) was 38.1% for monozygotic twins compared to 0% for dizygotic twins (Novak, Keuthen, Stewart, & Pauls, 2009). Taken together, these studies suggest heritability is an important component in the etiology of TTM.


ED also appears to have a familial component. In a study with 60 patients with skin-picking disorder, Odlaug & Grant (2012) found 28.3% of first-degree family members also met criteria for the disorder. Another study found that 43% of 40 patients with ED had first-degree relatives with skin-picking symptoms (Neziroglu, Rabinowitz, Breytman, & Jacofsky, 2008). Further in support of a heritability component in the etiology of ED, Monzani and colleagues (2012) found that clinically significant skin picking was reported by 1.2% of twins, with higher concordance for monozygotic than dizygotic twins. Within this female sample, genetic factors accounted for 40% of the variance, with the remaining variance attributable to nonshared environmental factors. Future studies are needed with homogenous samples, diagnosed with DSM-5 criteria, to establish heritability of ED.


Neuroanatomy and Neurobiology


Extant literature supports an association between OCD and impairments of the brain’s corticostriatal systems, which include organized neural circuits that connect the basal ganglia, thalamus, and cortex. For instance, fMRI findings suggest that patients with OCD exhibit impairments in functional connectivity of both the ventral and dorsal corticostriatal systems, with a direct link between ventral corticostriatal connectivity and symptom severity (Harrison et al., 2009). Although these authors were able to show system-wide differences in connectivity, the sample size was too small to determine the effects of specific symptom dimensions. More recent research has focused on a multidimensional model that examines direct links between major OCD symptom dimensions and structural and functional brain indicators (Menzies et al., 2010).


In a recent study, investigators evaluated the influence of OCD symptom dimensions on brain corticostriatal functional systems (Harrison et al., 2013). Results found a shared connectivity involving the ventral striatum and orbitofrontal cortex that was related to overall severity level, but independent of specific symptom dimensions. Rather, distinct anatomical relationships between the severity of symptom dimensions and connectivity were observed, with aggression symptoms moderating connectivity in the ventral striatum, amygdala, and ventromedial frontal cortex, and sexual/religious symptoms affecting ventral striatal-insular connectivity. This recent data suggests common pathophysiological changes in orbitofrontal-striatal regions across various forms of OCD. Further, Beucke and colleagues (2013) examined abnormal connectivity in the orbitofrontal cortex in medicated and nonmedicated OCD patients and matched normal controls. Consistent with previous research, the orbitofrontal cortex and the basal ganglia showed greater connectivity in unmedicated OCD patients, suggesting that antidepressant medication may reduce brain connectivity in OCD patients. It is also interesting to note that more distant connectivity was observed in this study, highlighting the need for future research to determine the extent of hyper connectivity outside of corticostriatal circuitry (Beucke et al., 2013).


Structural magnetic resonance imaging (MRI) studies with BDD patients have shown caudate nucleus asymmetry (Rauch et al., 2003) and orbitofrontal cortex volume abnormalities (Atmaca et al., 2010), with both studies finding an increase in white matter volume in patients with BDD. White matter microstructure was recently evaluated by diffusion weighted MRI to examine connectivity among structures thought to be involved in BDD (Feusner et al., 2013). Results of the study suggest a relationship between impairments in insight and fiber disorganization in tracts connecting visual with emotional and memory processing. Arienzo and colleagues (2013) also conducted a brain network analysis and found disturbances in whole brain organization. Specifically, abnormal connectivity between regions involved in lower-order visual processing and higher-order visual and emotional processing was observed. Further, a study using single photon emission computed topography (SPECT) imaging found occipital perfusion and parietal abnormalities in BDD (Carey, Seedat, Warwick, van Heerden, & Stein, 2004), which is interesting as parietal dysfunction has also been shown to be associated with disturbances in body image (Trimble, 1988). Although more research is needed, these studies suggest disturbances in information processing in patients with BDD.


Given the perceived defects that patients with BDD report about their appearance, and the visuospatial processing deficits found within neuropsychological research, it is likely that disturbances in visual perceptual or visuospatial processing may be present in patients with BDD. In a neuroimaging study investigating visual processing of others’ faces in patients with BDD compared to controls, fMRI was used to scan while subjects looked at photographs of unknown faces that were unaltered or altered to contain primarily low or high detail information (Feusner, Townsend, Bystritsky, & Bookheimer, 2007). BDD patients evidenced greater left hemisphere activity relative to controls for all image types but particularly to the low-detail faces. This laterality imbalance may suggest greater detailed facial processing and less holistic processing. In a more recent fMRI study, BDD subjects viewed photographs of their own face and a familiar face that had been altered or unaltered to include high or low detail information (Feusner, Neziroglu, Wilhelm, Mancusi, & Bohon, 2010). Again, BDD subjects showed relative hypoactivity in visual cortical systems for low detail photographs. To investigate if BDD patients have a more general abnormality in visual processing, BDD patients were scanned while looking at pictures of houses (as opposed to faces). The BDD group showed abnormal relative hypoactivity in left visual association areas for low detail images and hyperactivity of prefrontal systems for high detail images (Feusner et al., 2010). Thus, it appears that BDD patients may exhibit general abnormalities in lower and higher order visual processing.


Preliminary evidence suggests that hoarding symptoms may have a different neural substrate than OCD. Studies of animal hoarding and hoarding due to brain damage or dementia have implicated the subcortical limbic structures and the ventromedial prefrontal cortex as important in hoarding behavior (see Mataix-Cols, Pertusa, & Snowdon, 2011 for a review). Studies of humans with compulsive hoarding have focused on the same brain areas and found similar results. Saxena and colleagues (2004) found that compulsive hoarders show a unique pattern of abnormal resting-state brain function relative to that of normal controls and nonhoarding OCD patients. Specifically, the hoarding group evidenced abnormally low activity (reduced glucose metabolism) in the posterior cingulate cortex compared to normal controls and the dorsal anterior cingulate when compared to nonhoarding OCD patients.


Brain activity of hoarding and nonhoarding OCD patients was compared to normal controls in a symptom-provocation study (An et al., 2009). During an fMRI assessment, these subjects were asked to imagine throwing away objects that belonged to them while shown pictures of the items. The OCD patients with hoarding symptoms showed more reactivity in the ventromedial prefrontal cortex (VMPFC) than the other groups. In an exploratory study, Tolin, Kiehl, Worhunsky, Book, & Maltby (2009) conducted fMRI assessment of a small group of severe hoarders (n = 12; only 2 with OCD diagnosis) and normal controls. When deciding whether to keep or discard real personal items, individuals with hoarding symptoms showed greater activity in the left lateral orbitofrontal cortex and parahippocampal gyrus compared to controls.


In a more recent study, neural activity was measured by fMRI in patients with well-defined primary HD (as proposed for DSM-5 in Mataix-Cols et al., 2010) and compared to patients with OCD and normal controls (Tolin et al., 2012). The task involved real-time, binding decisions that had to be made about whether to keep or abandon actual belongings compared to control items. The HD group discarded significantly fewer personal items than the OCD and control groups with no differences in decisions to discard control items. With regard to neural activity, the HD group differed from OCD and normal controls in the anterior cingulate cortex and the left and right insular cortex. Taken together, these studies suggest that the ventromedial prefrontal/cingulate and medial temporal regions may be involved in hoarding behavior.


Imaging studies of TTM have been somewhat inconsistent. Early studies of hair pulling (then defined as an impulse control disorder NOS in DSM-IV

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Jun 10, 2016 | Posted by in PSYCHOLOGY | Comments Off on Obsessive-Compulsive and Related Disorders

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