Dean McKay and Eric A. Storch (eds.)Handbook of Assessing Variants and Complications in Anxiety Disorders201310.1007/978-1-4614-6452-5_8© Springer Science+Business Media New York 2013
8. Functional Assessment of Comorbid and Secondary Disorders: Identifying Conditions for Primary Treatment
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Ferkauf Graduate School of Psychology, Yeshiva University, 1300 Morris Park Avenue, Rousso 135, Bronx, NY 10461, USA
Abstract
Anxiety disorders often present for treatment with more than one additional diagnosis. Determining which diagnosis should be considered primary, and even when diagnoses are comorbid deciding which should be targeted first, is difficult to determine. This chapter discusses diagnoses that commonly co-occur with anxiety disorders, in adults and children. Functional assessment methods are described as a template for determining condition for treatment target.
Anxiety disorders are among the most prevalent psychiatric diagnoses in adults and children (Costello, Mustillo, Erkanli, Keeler, & Angold, 2003; Curry, March, & Hervey, 2004; Kessler, Chiu, Demler, & Walters, 2005; Merikangas et al., 2010). Thus, it is common for clinicians to encounter many individuals seeking treatment for anxiety. Given the nature of anxiety, those with an anxiety disorder tend to present their anxious symptoms as the primary, or perhaps only, complaint when they make the decision to seek treatment. This tendency holds even when there may be other factors negatively impacting their day-to-day functioning. Furthermore, there are several other diagnoses that tend to co-occur with anxiety disorders, including a second anxiety disorder, depression, Attention-Deficit Hyperactivity Disorder (ADHD), or substance use disorder.
The inclination to focus on anxiety as the primary treatment target is likely due to the prominent physiological reaction that accompanies anxiety response. As a result, it can be difficult to see other associated emotional or behavioral problems as more or equally important than reducing anxiety response and/or their associated somatic components. Because anxiety disorders are so frequently encountered and they often include physiological distress that is difficult to tolerate, it becomes the task of the provider to conduct a thorough assessment to ensure that all relevant treatment targets have been identified. Individuals may not be aware of other psychiatric disorders that are present, or they may not be motivated to address those disorders because the anxiety symptoms are more intolerable and disabling.
This chapter discusses disorders that frequently co-occur with anxiety disorders. It also outlines approaches to functional assessment of these conditions in the context of anxiety. The chapter concludes by presenting the evidence that treatment of these comorbid disorders may warrant priority in the treatment plan in order for anxiety to be effectively and efficiently treated.
Disorders That Frequently Co-occur with Anxiety Disorders
Anxiety disorders often co-occur with other psychiatric diagnoses across the lifespan. The comorbid diagnoses may be homotypic (i.e., another anxiety disorder) or heterotypic (i.e., another psychiatric disorder). This section covers the rates of comorbidity for the most frequently occurring diagnoses among youth and adults. Although the age groups are addressed separately, there is overlap. Specifically, homotypic and mood disorder comorbidity are discussed for both young people and adults. Additionally, comorbidity with disruptive behavior disorders and Pervasive Developmental Disorders (PDD) are addressed for youth. Substance use disorder comorbidity is reviewed for adults, but it is important to bear in mind that problematic substance use in the context of anxiety may also occur in adolescents.
Children and Adolescents
Psychiatric comorbidity is common among youth. Data from the Great Smoky Mountains Study indicate that approximately one-quarter of all youth with a psychiatric diagnosis have two or more diagnoses (Costello et al., 2003). Brady and Kendall (1992) reported a 16% comorbidity rate in a community sample of children and adolescents who were not seeking treatment. The comorbidity rates ranged from 28 to 62% in clinical samples of youth who were seeking treatment. Children and adolescents diagnosed with anxiety disorders are no exception. Generally speaking, childhood disorders can be broadly classified as either internalizing (i.e., mood disorders) or externalizing (i.e., disruptive behavior disorders) (Krueger & Piasecki, 2002). Among youth, both classes of disorders frequently co-occur with anxiety.
Homotypic Comorbidity
In a representative sample of American teens, Burstein, Swanson, He, and Merikangas (2010) found that just less than one-third of youth with an anxiety disorder have more than one anxiety diagnosis. Esbjørn, Hoeyer, Dyrborg, Leth, and Kendall (2010) recently investigated the patterns of comorbidity among a large national sample of children and adolescents admitted for treatment in Denmark over a 3-year period. They found a 5.7% prevalence rate of anxiety disorders, and furthermore, they found that 2.8% of these anxious youth had more than one anxiety diagnosis.
In a similar study, Hammerness et al. (2008) examined the diagnoses that co-occurred with anxiety disorders among a large sample of children referred for treatment at a clinic in the United States over the course of more than a decade. Among youth with an anxiety disorder, they found that 46% of youth had one anxiety disorder, while 28% had two anxiety diagnoses. Nearly half the anxious sample had a diagnosis of separation anxiety disorder (SAD; 49%) or overanxious disorder (47%). In terms of comorbidity, Hammerness and colleagues found that having any anxiety disorder significantly increased the risk for having an additional anxiety disorder, but the risk was found to be greatest for panic disorder (PD) and agoraphobia.
There is some evidence that different anxiety disorders may be more closely associated with different comorbid diagnoses. Accordingly, the clinician can use this knowledge of these patterns to guide thorough assessment for comorbid conditions. Verduin and Kendall (2003) found that youth with a primary diagnosis of SAD or Generalized Anxiety Disorder (GAD) were also more likely to have a comorbid Specific Phobia (SP) than youth with a Social Phobia (SoP) diagnosis.
Kim et al. (2010) found high rates of homotypic comorbidity with SP among a sample of Korean school children aged 6–17 years. These researchers also found a 1-year prevalence rate of 7.9% for SP. Most respondents reported animal phobias (49.2%), followed by nature–environment type (32.4%), blood–injury–injection (BII) type (18.4%), and situation phobias (0.2%). Among these youth who were diagnosed with a SP, 28.1% had at least one comorbid psychiatric diagnosis, and compared to controls, those with a SP had significantly higher rates of comorbid anxiety disorders. The results also indicated a different pattern of comorbidity for the different subtypes. Individuals with animal phobia and nature–environment phobia were found to be significantly more likely to have an additional anxiety disorder diagnosis.
Mood Disorders
There is an extensive body of literature that establishes high rates of comorbidity between depression and anxiety disorders among youth (Clark & Watson, 1991). Esbjørn et al. (2010) found a large proportion of anxious youth had a heterotypic comorbidity (42.9%), but the anxiety diagnosis was the primary condition for treatment of most of the children in the sample (73.6%). Mood disorders were found be among the most frequently co-occurring diagnoses, particularly in the case of comorbidity with social phobia and specific phobias. Hammerness and colleagues compared youth with an anxiety disorder (excluding Obsessive–Compulsive Disorder [OCD]) with youth diagnosed with a disruptive behavior disorder (i.e., ADHD, Oppositional Defiant Disorder [ODD], or Conduct Disorder [CD]). Compared to children with a disruptive behavior disorder, children with an anxiety disorder had significantly higher rates of major depression (63% vs. 36%) and bipolar disorder (24% vs. 12%). Verduin and Kendall (2003) found that comorbid mood disorders were more common among children with GAD as compared to children with SAD.
Externalizing Disorders
Externalizing disorders also frequently co-occur with anxiety disorders. Angold, Costello, and Erkanli (1999) found that the presence of comorbid ADHD ranged from 0 to 16.7%. Comorbid ODD or CD was reported in 7.9–33.3% of youth with anxiety disorders. Esbjørn et al. (2010) also found that ADHD was among the most common comorbidity, particularly among youth diagnosed with GAD or other anxiety (i.e., not SAD, GAD, SoP, or SP, which were the other anxiety disorders studied, nor OCD or Posttraumatic Stress Disorder [PTSD], which were not included in this study). Verduin and Kendall (2003) also found high rates of comorbid anxiety and externalizing disorders in their sample. They reported that 17.6% of their sample met criteria for comorbid ADHD and 9.5% for comorbid ODD. However, they did not find a significant difference in rates of externalizing diagnoses for the different anxiety diagnoses. Kim et al. (2010) found that youth with SP had significantly higher rates of ADHD and ODD compared to controls. Specifically, animal phobia was significantly associated with ODD, and BII phobia was significantly associated with ADHD.
Pervasive Developmental Disorders
There is some evidence that there is high comorbidity between PDD, including autistic disorder, Asperger’s disorder, and PDD not otherwise specified (PDD-NOS), and anxiety disorders. Children with an anxiety disorder have been found to have a significantly higher amount of comorbid PDD compared to children with an externalizing disorder diagnosis (5% vs. 2%; Hammerness et al., 2008). Esbjørn et al. (2010) also found that PDD was commonly comorbid among youth with anxiety in their sample, but, in almost all cases, it was found to be an additional secondary diagnosis. There is evidence that among youth diagnosed with PDD-NOS, a majority may also meet diagnostic criteria for an anxiety disorder with the highest rates of comorbidity found for specific phobias (de Bruin, Ferdinand, Meester, de Nijs, & Verheij, 2007; Muris, Steerneman, Merckelbach, Holdrinet, & Meesters, 1998).
Davis et al. (2011) found that among children with PDD, anxiety increased as social skills deficits increased. This indicates that anxiety may arise as a result of avoidance of social situations and people with whom social interaction is expected. Thus, comorbid anxiety is particularly debilitating because of its additional negative effects on performance in school, as well as functioning in social settings and the home. Sze and Wood (2007) referred to comorbid anxiety in the context of PDD as “an additional barrier to children’s overall adjustment” (p. 134).
Adults
As is the case among youth, many adults with anxiety disorders also experience comorbid mental disorders. Among individuals who participated in the National Comorbidity Study (NCS), 19.3% endorsed having any anxiety disorder within the past 12 months (Kessler et al., 1997). Merely 21.5% of these participants did not have any additional diagnoses during their lifetime (i.e., pure anxiety disorder). About the same number of individuals (19.9%) did not report any additional diagnoses during the 12-month period. Yet, they did endorse having a mental disorder previously in their lifetime. The remaining majority of participants with an anxiety disorder (58.6%) reported having another mental disorder in the same 12-month period. There is considerable overlap between youth and adults in terms of patterns of comorbidity.
Homotypic Comorbidity
Frequently, adults diagnosed with one anxiety disorder also tend to have a secondary anxiety disorder diagnosis (Barlow, 1988). In a sample of 130 clients seeking treatment for anxiety, Sanderson, DiNardo, Rapee, and Barlow (1990) found that most individuals (70%) met criteria for another diagnosis. Of those clients with a comorbid diagnosis, approximately one-third were diagnosed with secondary SP or SoP.
Mood Disorders
There is plentiful empirical evidence that anxiety disorders and depression co-occur throughout the lifespan (Kessler et al., 1998; Wittchen, 1996). Rivas-Vazquez, Saffa-Biller, Ruiz, Blais, and Rivas-Vazquez (2004) described anxiety and mood disorder comorbidity as “more the rule rather than the exception” (p. 74). Recent research indicates that the onset of anxiety disorders typically precedes the onset of depression, and furthermore, an anxiety diagnosis increases the risk for later depression at a 5-year follow-up (Wittchen, Beesdo, Bittner, & Goodwin, 2003). Comorbid depression and anxiety are associated with a poorer prognosis. Individuals with both anxiety and depression typically have more severe symptoms, respond less favorably to treatment, and are at higher risk for suicide (Rivas-Vazquez et al.). Because having an anxiety disorder increases one’s risk for later onset of depression, there is a pressing need for early detection and treatment of depression in the context of anxiety to improve prognosis.
Research findings specify that PD and GAD are associated with the highest levels of comorbidity with depression. In the NCS sample, 55% of the participants with lifetime PD also reported a lifetime diagnosis of depression. Furthermore, approximately the same number of participants with lifetime panic attacks (but not PD) also met criteria for depression (Kessler et al., 1998). Likewise, most of the NCS participants with a 12-month GAD diagnosis (58.1%) also met criteria for major depression at 12 months (Kessler, DuPont, Berglund, & Wittchen, 1999).
Substance Use Disorders
Substance use disorders may co-occur with anxiety disorders among adolescents and adults (Lopez, Turner, & Saavedra, 2005). Data from the Epidemiological Catchment Area (ECA) study indicated that 15% of individuals with an anxiety disorder also reported a SUD within the previous 12 months (Regier, Rae, Narrow, Kaelber, & Schatzberg, 1998). In an international epidemiological study, it was found that nearly half of the individuals with any lifetime anxiety disorder diagnosis also met diagnostic criteria for drug dependence (Merikangas et al., 1998). Kessler et al. (1997) found that among men and women who participated in the NCS, many of those individuals who endorsed alcohol dependence reported that their alcohol dependence was secondary to the onset of an anxiety disorder diagnosis (i.e., 21.8% of men and 49.7% of women). The co-occurrence of substance use disorders seems to be most closely linked with a PTSD diagnosis (Hofmann, Richey, Kashdan, & McKnight, 2009; Lopez et al.).
Functional Assessment
The goals of functional assessment are to determine the frequency, intensity, or duration of problematic target behaviors, as well as to determine the antecedent conditions under which the behaviors occur (i.e., eliciting and discriminative stimuli), perceived functions, and consequences of these target behaviors (Martin & Pear, 2007). In terms of treatment planning, functional assessment of anxiety disorders may serve to identify antecedent conditions that may be altered to reduce the likelihood of experiencing anxiety. The reinforcement contingencies that are maintaining the behavior may be identified. The sources of reinforcement may also be eliminated to decrease the target behavior.
Haynes and O’Brien (1990) defined functional analysis as “the identification of important, controllable, causal functional relationships applicable to a specified set of target behaviors for an individual client” (p. 654). This conceptualization focuses on identifying variables that meet three criteria (i.e., important, controllable, and causal), and one can accordingly target these variables for treatment. While there may be many variables associated with a target behavior, not all will be clinically useful. For instance, there may be important variables that are causal but not controllable (e.g., exposure to a traumatic event leading to the development of PTSD).
There are three main foci in a functional analysis: the antecedents, target behavior(s), and direct consequences. Target behaviors are usually triggered by a predictable set of antecedents or environmental conditions (e.g., drinking alcohol may be immediately preceded by an interpersonal conflict). Most antecedents occur just prior to or at the same time as the onset of the behavior. The specific consequences arise as a result of performing the target behavior. In a functional assessment, the target behavior(s) is theorized to serve some function. Analysis of the antecedents and consequences help the clinician to derive a hypothesis about what is maintaining the target behavior. Typically, behaviors may function to help individuals obtain something which they desire (i.e., positive reinforcement) or to help individuals avoid something they find aversive (i.e., negative reinforcement). Thus, an individual may drink to receive attention from other bar patrons, or he may drink to escape the experience of painful emotions by becoming intoxicated.
Functional assessment may be initiated when treatment is not progressing adequately. It may be that the selected treatment is not effectively addressing the antecedents and consequences maintaining a problematic behavior. On the other hand, it is recommended that functional assessment be implemented at the outset of treatment to make sure that the relevant environmental contexts can be taken into account during treatment planning. Based on the data gathered during functional assessment, treatment components may be altered or entirely omitted depending on the particular functions that the behavior is serving. This ensures that the intervention will focus on the idiosyncratic variables that have been maintaining behavior problems for the individual. Despite the strong connection between conducting a thorough functional assessment and identifying the most important targets for treatment, evidence suggests that this is an under-utilized approach to treatment planning. Perhaps it is often not included in assessment because it takes more time and effort than diagnosis (Virués-Ortega & Haynes, 2005).
Functional Assessment Strategies
Functional assessment can be conducted via three different methods. It is recommended that multiple assessment types be used to determine causal functional relationships most efficiently (Haynes & O’Brien, 1990). The first method is indirect assessment. Other people familiar with the individual’s behavior are asked to complete relevant questions that provide information about the instances in which they have observed the problem behavior in the past. Because this is an indirect method, it is susceptible to errors and bias and may not be as reliable as direct methods of functional assessment.
The second method of functional assessment is to observe the individual performing the problem behavior in her or his natural setting. When possible to observe the individual unobtrusively, this method can provide meaningful data relevant to the problem behavior(s). An advantage of this type of live observation is that the clinician may be able to identify aspects of the behavioral sequence (i.e., antecedent conditions and consequences) that are currently outside the awareness of the individual and those interacting with him or her.
The final method for functional assessment is to conduct a functional analysis or an experimental functional assessment. In this type of assessment, the practitioner sets up and alters the antecedent conditions and consequences to elicit the problem behavior and note the patterns of performance under these different conditions. This method serves to support or refute hypotheses made about the function of problem behavior for the individual. For example, suppose that a client was interested in reducing drinking behavior in social situations. A clinician might set up an experimental functional assessment situation in which the client is faced with a social interaction with a stranger (i.e., the hypothesized antecedent), but not given the opportunity to consume an alcoholic beverage (i.e., the target behavior).
Using Functional Analysis to Assess for Comorbidity
Functional assessment is a particularly valuable part of any comprehensive assessment with children because their level of cognitive development may limit their ability to reflect upon and report their anxious thoughts (Beidel & Turner, 2005). Furthermore, it has been noted that anxiety may not be easily recognized in children because young people tend to use avoidance skillfully to completely evade anxious feelings and to report somatic symptoms rather than identifying and reporting their worries or fears (Emslie, 2008). Although these barriers to valid assessment are more frequently discussed in the context of diagnosis with young people, they apply equally well to some adult populations.
The use of functional analysis bypasses the need for accurate self-report and allows the clinician to directly observe the problem behaviors and their impact on functioning. It is also an outstanding tool for assessing comorbid conditions because the clinician is able to identify the extent to which overlapping features of the separate disorders are connected as antecedent conditions or direct consequences of one another. Behavioral analysis of presenting symptoms was specifically recommended by Rachman (1991) as a strategy for managing comorbidity.
Homotypic Comorbidity
When clients seek treatment for a primary anxiety disorder, a functional analysis should be conducted to determine if symptoms of an additional anxiety disorder are present. The diagnostic criteria for many of the anxiety disorders include a specification that the disorder should only be diagnosed if not better accounted for by another anxiety diagnosis (American Psychiatric Association, 2000). For example, phobic avoidance should not be interpreted as evidence for SP if it is better explained as avoidance of some object due to an OCD obsession. Thus, a thorough functional assessment should aim to identify the conditions immediately before and after escape from (or avoidance of) feared objects, people, or situations. The data from functional assessment may assist the clinician in determining whether different stimuli are feared in the context of a single anxiety disorder (e.g., avoiding dogs and public bathrooms because of obsessions about contagion in the context of OCD) or whether they are associated with independent anxiety disorders (i.e., SP and OCD).
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