آسیب شناسی روانی همراه با اختلال طیف اوتیسم در کودکان: نمای کلی

Comorbidity, the co-occurrence of two or more disorders in the same person, has been a topic receiving considerable attention in the child psychopathology literature overall. Despite many publications in the ADHD, depression and other child literatures, autism spectrum disorder has not received such scrutiny. The purpose of this review will be to discuss the available evidence. We address specific variables in diagnosis and classification of comorbid symptoms, and propose potential avenues for research and practice with respect to differential diagnosis. A brief discussion of the implications for treatment is also provided.

Comorbidity, defined here as the occurrence of two or more forms of psychopathology in the same person, has received a considerable amount of attention in the child literature. Perhaps the most prominent of these areas of research focuses on attention-deficit/hyperactivity disorder (ADHD) where comorbidity has been reported to be as high as 50% (Anderson, Williams, McGee, & Silva, 1987; Bird et al., 1988; Caron & Rutter, 1991). Similarly, for those ADHD children referred to a clinic, 87% have a comorbid condition and 67% have two or more additional forms of psychopathology (Kadesjo & Gillberg, 2001). Other childhood disorders have also been studied, although to a lesser degree. Angold, Costello, and Erkanli (1999) for example, found that comorbidity between depression with ADHD, anxiety or conduct/oppositional defiant disorder was common. Similarly, children and adolescents with eating disorders are likely to exhibit a variety of psychopathology with comorbidity rates as high as 90% (Lewinsohn, Striegel-Moore, & Seeley, 2000). Substance abuse, anxiety and mood disorders appear to be the most common comorbid conditions (Grilo, Levy, Becker, Edell, & McGlashan, 1996). Perhaps not surprisingly, multiple disorders present in the same person result in more frequent mental health referrals compared to children who evince only one disorder (Mash & Barkley, 2003). Comorbidity in the assessment of autism spectrum disorder (ASD) is a topic that has infrequently been addressed, particularly when compared to the childhood disorders noted above. When the topic has been discussed, it has often been in the context of ASD with intellectual disability (ID) since, with the exception of Asperger's syndrome, these two conditions co-occur frequently, and symptoms of autism, particularly language delays, stereotypies, and self-injury, increase as the severity of ID increases (Wing & Gould, 1979). For the purposes of this review, we will forgo that discussion and focus on specific forms of emotional problems and challenging behaviors which constitute DSM-IV diagnoses, such as self-injury, stereotypies, and conduct disorder. However, the reader should be aware that disagreement exists over whether many of these diagnoses warrant separate categories or should be viewed as symptom clusters of ASD (AACAP, 1999). Autism can be distinguished from psychosis while stereotypy and self-injury are not differentially diagnostic between autism and ID (Matese, Matson, & Sevin, 1994; Sevin et al., 1995). Given that they are not diagnostic of ASD, but may co-occur with the disorder, describing these behaviors as comorbid conditions versus core features of an ASD appear to be more consistent with the data. Some researchers have debated over whether comorbidity, at least with some disorders, has perhaps slowed the development of knowledge in this area. However, the notion that “standard diagnostic instruments should be employed to delineate impairment, including the full range of diagnosable disorders,” has been asserted (Kazdin, 1993). Kazdin (1993) made these remarks with respect to treatment outcome research with ASD. However, diagnosis would appear to be equally applicable with respect to this point. An additional confounding variable is the complexity of diagnosing ASD and its various subtypes in children, the majority of whom are also ID (Long, Wood, & Holmes, 2000). While Asperger's does not involve ID, the more prevalent conditions of PDD and autism do involve high rates of the latter condition. Autism in particular has been studied in relationship to ID and occurs in most cases (Folstein & Rutter, 1987; Ritvo et al., 1989). In the latter study, 66% of their sample of autistic children scored below 70 on an I.Q. test. Given the overlap in ASD and ID, it is difficult and perhaps not particularly profitable to discuss issues of psychopathology that occur conjointly in one of these conditions taken alone. In fact, many of the same factors that make definition and diagnosis difficult with one, applies to another. And, with the exception of Asperger's syndrome, most cases will involve ASD and ID together. Second, it is asserted that diagnosing comorbid psychopathology in these persons is appropriate, although the symptoms may vary from those seen in the general population. At present it seems reasonable to conclude that issues of comorbidity are poorly understood (Matson & Barrett, 1982; Ghaziuddin, Ghaziuddin, & Greden, 2002). Third, there is considerable heterogeneity in symptoms of ASD. This variability leads to additional complications regarding what constitutes core symptoms and whether the disorder should be conceptualized on a dimensional scale with subtyping of ASD or whether distinct disorders within the continuum of ASD should be specified (e.g. PDD-NOS, autism, Asperger's syndrome) (Sturmey & Sevin, 1994; Szatmari, Volkmar, & Walter, 1995). 1. Types of comorbid psychopathology Sporadically, papers have appeared regarding comorbidity in ASD, although they are almost exclusively about one subtype, autism. This phenomenon is related to the fact that autism has received most of the research attention in the ASD spectrum literature until very recently. Even now, the majority of published studies in ASD involve autism. Asperger's syndrome, which some describe as older, higher intellectually functioning persons with autism, is beginning to receive more attention. However, by the nature of the literature, and the fact that Asperger's syndrome is often not diagnosed until late childhood or early adolescence, the bulk of the review on ASD will be autism studies (Howlin, 2003 and Howlin and Moore, 1997; Scott, Baron-Cohen, Bolton, & Brayne, 2002). We have limited our discussion of comorbid disorders to those discussed in the literature. Thus, while an exhaustive list may not be presented here, those comorbid conditions considered most relevant by ASD researchers at this time have been discussed. 1.1. Mood disorders Mood disorders can be broken down into major depression and bipolar disorder. Both conditions are potentially very debilitating. Ghaziuddin and colleagues have been the most prolific publishers to date on depression and its potential co-occurrence with autism (Ghaziuddin & Greden, 1998; Ghaziuddin, Alessi, & Greden, 1995; Ghaziuddin et al., 2002 and Ghaziuddin and Tsai, 1991; Ghaziuddin, Tsai, & Ghaziuddin, 1991). The reader is referred to these articles for a more detailed review of the topic. One general conclusion that can be arrived at from the work of these authors and others is that depression is a comorbid condition with autism, being diagnosed in 2% of the children studied (Ghaziuddin, Tsai, & Ghaziuddin, 1992). Children with Asperger's syndrome have comorbidity rates as high as 30% (Ghaziuddin, Weidmer-Mikhail, & Ghaziuddin, 1998; Wing, 1981). Ghaziuddin et al. (2002) assert that depression is probably the most frequent form of comorbid psychopathology with ASD. They also state that these rates are probably low estimates, given the general lack of measures for assessing comorbidity in ASD. The meager findings on depression in ASD are consistent with a larger, but still inadequate ID literature. Depression in this latter group is considered to occur, and at a high incidence and prevalence (Kazdin, Matson, & Senatore, 1983; Matson, Kazdin, & Senatore, 1984). Additionally, depressed persons with mild ID are likely to evince symptomatology consistent with behavior observed in the general population with major depression (Matson, 1986 and Matson et al., 1988). However, those with severe ID are likely to display somewhat different psychopathology symptom profiles, particularly in poverty of verbal behavior. Thus, focusing assessment largely on vegetative symptoms and family history has been suggested (Ghaziuddin et al., 2002 and Matson et al., 1999). Severity of ID is likely to complicate efforts at diagnosis of comorbid psychopathology. Additionally, more severe ASD core symptom clusters are likely to mask or reconfigure depression profiles. How this occurs and the implications for differential diagnosis, prognosis, and treatment await much needed investigation. It should be stressed that identifying comorbidity of depression and ASD is more than an academic exercise. Depression can negatively impact long-term outcome. Second, but related to the first point, depression may put the person with ASD at risk for suicide, greater levels of withdrawal, non-compliance and aggression. The occurrence, recognition, causes and targeting of these behaviors/symptoms has major implications for treatment. Additionally, these problems can negatively impact the family unit, resulting in increased stress and conflict (Gold, 1993). Data then on developments in this research, to date, might best be described as slow and halting. Researchers have in the past suggested that diagnosis of major depression occurs less frequently in children than in adolescents or adulthood, thus partially explaining the lack of inclusion of outcome measure in this domain for program studies of young children with ASD (Lainhart & Folstein, 1994; Pollard & Prendergast, 2004). However, until recently there has been a general lack of measures for diagnosing children with depression in general, further compounding this problem. Bipolar disorder is a second mood disorder and a very serious condition which has proven both difficult to differentially diagnose and treat (Matson et al., in press). For 70% of the childhood cases in the general population, the disorder initially presents as major depression (Roberston et al., 1994). Additionally, symptoms may wax and wane (Findling et al., 2001) and comorbidity with other psychopathologies, regardless of the occurrence of ASDs, such as anxiety and ADHD are common (Carlson, 1998 and Masi et al., 2001). The literature with the ASD population is almost non-existent at this point. Gillberg (1985) has described a single case of bipolar disorder in Asperger's syndrome and Realmuto and August (1991) describe three autistic individuals where some bipolar features were present. Much of the problem here is that until very recently bipolar research has been conducted almost exclusively with adults, and the conceptualization of bipolar and subtyping (e.g. bipolar I, bipolar II, schizoaffective, etc.) has been in flux. Reliable and valid methods of assessing the condition in children are beginning to be codified. As the area matures, implications for the ASD population are likely to receive more attention. 1.2. Phobias/OCD/anxiety Fears and phobias among children with ASD have been largely ignored in the literature. However, a few single case treatment studies of ASD children with phobias have been published. Luiselli (1978) treated an autistic child who feared riding a bus. Love, Matson, and West (1990) trained mothers to effectively deal with their autistic children's fears of going outside and of bathroom showers, and Luscre and Center (1996) developed a treatment for ASD children who had dental fears. Most recently, Rapp, Vollmer, and Hovanetz (2005) treated swimming pool avoidance in an autistic adolescent girl. The first systematic group study of phobias was by Matson and Love (1990). They looked at the intensity of fears and phobias of autistic children by matching them to normal same age peers. Autistic children were more fearful of thunderstorms, dark places, large crowds, dark rooms or closets, going to bed in the dark, and closed places. The fears and phobias most common in the matched normal developing peers showed little overlap with the autistic group. More recently, Evans, Canavera, Kleinpeter, Maccubbin, and Taga (2005) replicated and extended this study with 25 ASD children, 43 children with Down syndrome, 45 children matched on mental age and 37 normal developing peers who were chronologically matched. These authors findings were similar to the Matson and Love (1990) data. The ASD children evinced a different set of fear and phobia priorities than other children studied. Medical, animal and situation phobias were more common than in the others groups studied. The authors note that an ASD diagnosis is predictive of certain fears and phobias, which the clinician should watch for, and which may require clinical attention. 1.3. Anxiety and obsessions Anxiety appears to overlap particularly with depression and ASD. However, controversy exists not only with respect to whether ASD is separate from anxiety, but also with respect to fears, phobias and depression. The research supporting comorbidity is sparse while data refuting a comorbidity hypothesis is non-existent. Woodard, Groden, Goodwin, Shanower, and Bianco (2005) treated a 10-year-old autistic boy who they also describe as being diagnosed with generalized anxiety disorder. The authors do not report who gave the diagnosis or the criteria or methods used. However, using an ABAB single case design, he was treated with 0.5 mg BID of dextromethorphan. The authors report marked improvements including less frequent communications about being anxious. He was also reported to be more cooperative, empathetic, and responsive to consequences. Behaviors related to obsessive compulsive disorder (OCD) are also characterized by anxiety. Perhaps more so than any other disorder, concern about whether OCD can be separate from ASD has been debated. A person with OCD engages in repetitive acts with the goal of reduced anxiety in mind. From a definitional standpoint, ASD symptoms would also meet this criterion. Three factors which would need to be met include engagement in acts typical of OCD, such as frequent hand washing to kill germs, responsiveness to interventions typically effective for OCD (validity), and a core set of OCD symptoms that would be above and beyond the typical obsessive symptoms seen in the model ASD case. Studies that look at these factors have yet to be done. Until then, conjecture on this topic is likely to flourish. Charlop-Christy and Haymes (1996) operationally defined obsessions as continuous verbal requests across settings in their study. They note that DSM-IV criteria were used, but it is unclear whether the DSM-IV criteria applied were for OCD and/or ASD. Nonetheless, it is instructive to see these targets described in such a manner for ASD children. The authors label theses behaviors as aberrant and the authors appear to support the notion that in this context, the obsessions (e.g. looking at maps, tossing a ball, playing with a helicopter), were a form of stereotypic behaviors. They also noted, however, that some autistic children display obsessive behaviors while others do not. This article, thus, provides an interesting exemplar of obsessive behavior as part of the ASD syndrome versus part of a distinct comorbid condition. At this point, more descriptive data are needed on frequency, intensity, and rate of behaviors/symptoms to further delineate if distinct OCD occurs in ASD, and if so, when and at what rate. 1.4. Psychosis and ASD Childhood schizophrenia and autism have been seen as overlapping conditions, and in fact the terms were sometimes used interchangeably in the past. More recently, the conditions have been viewed as very distinct and ASD has been referred to as a developmental disorder (American Psychiatric Association, 1994). In a phrase becoming redundant at this point, little information directly testing this hypothesis has occurred. It is the case that many studies of ASD, autism in particular, have shown that these scales can effectively differentiate young children with autism from PDD or Asperger's syndrome (Cox et al., 1999), and receptive language disorders (Mildenberger, Sitter, Noterdaeme, & Amorosa, 2001). However, direct attempts to distinguish between schizophrenia and autism have been almost non-existent. McEachin, Smith, and Lovaas (1993) used the personality inventory for children and found at post-test that although very young autistic children were in the normal range on a variety of standardized measures of intelligence, adaptive behavior and maladaptive behavior, they tended to score higher on psychosis. These data are interesting when compared to Matese et al. (1994) who assessed the relationship between childhood psychosis and autism. Fifteen children with psychosis and 15 with autism from 4 to 13 years of age and matched on age, sex, and race, were compared on the real life rating scale (RLRS) and the childhood autism rating scale (CARS). The two groups differed in language, social skills, and adaptation to change. The psychotic children were relatively less impaired. These data support Cantor's (1988) claim that the two groups could be differentiated on language and social skills. Taken together, these preliminary results suggest that autism and childhood psychosis are distinct disorders. Also, the McEachin et al. (1993) data hint at the possibility that at least some children have comorbid diagnoses of autism and psychosis. However, Matese et al. (1994) lament the lack of sound diagnostic measures for childhood psychosis and point out that at one point or another, 20% of this group had received a PDD-NOS diagnosis. The comorbidity of ASD and psychosis is not confirmed by these data, but the data seem to support the value of additional research on this topic. Additionally, Cox et al. (1999) and Mildenberger et al. (2001) more recently have presented indirect evidence that autism can be differentially diagnosed from other ASDs. As can be seen however, the data are scant.