Repetitive behaviors in Tourette's syndrome and OCD with and without tics: what are the differences?

Gilles de la Tourette Syndrome (GTS) and obsessive-compulsive disorder (OCD) share obsessive-compulsive phenomena. The aims of this study were to compare the OC symptom distribution between GTS and OCD and to investigate whether a subdivision of these phenomena into obsessions, compulsions and 'impulsions' is useful in distinguishing GTS and OCD patients. Thirty-two GTS, 31 OCD (10 with tics, 21 without tics) and 29 control subjects were studied using the Leiden repetitive behaviors semi-structured interview to assess GTS as well as OCD-related behaviors. Each reported repetitive thought or action was evaluated on the presence of anxiety and on goal-directedness. This information was used to define whether the behavior was an obsession, compulsion, or 'impulsion'. Both the GTS and OCD study groups showed higher scores than control subjects on rating scales measuring depression, OC behavior and anxiety. In GTS, Y-BOCS severity scores and trait anxiety were lower than in the OCD groups. Furthermore, GTS patients differed from OCD patients in the distribution of symptoms. Aggressive repetitive thoughts, contamination worries and washing behaviors were reported more frequently by tic-free OCD, while mental play, echophenomena, touching and (self)-injurious behaviors were reported more frequently by GTS. OCD individuals with tics were intermediate, but closer to tic-free OCD. GTS individuals reported significantly more 'impulsions' and fewer obsessions and compulsions than OCD individuals with and without tics. Factor analysis revealed three factors accounting for 44% of the variance, resulting in an 'impulsive' factor related to GTS, a 'compulsive' factor related to OCD and an 'obsessive' factor related to tic-free OCD. In conclusion, OCD individuals reported more anxiety and goal-directedness associated with their behaviors than did GTS subjects. The distinction between obsessions, compulsions and impulsions is of importance in identifying Tourette-related vs. non-Tourette-related repetitions.     

The relationship between types and severity of repetitive behaviors in Gilles de la Tourette's disorder and obsessive-compulsive disorder

BACKGROUND: This study investigated which categories of obsessive-compulsive and Tourette-related behaviors in Gilles de la Tourette's disorder and obsessive-compulsive disorder (OCD) without tics are experienced as most severe across the study groups and what the differences are in symptom distribution between the study groups. METHOD: Fourteen subjects with both Tourette's disorder and OCD, 18 subjects with Tourette's only, 21 subjects with OCD (no tics), and 29 control subjects were studied using a semistructured interview designed to equally assess Tourette- and OCD-related behaviors according to DSM-III-R criteria. Each reported repetitive behavior was evaluated on the presence of anxiety and on goal-directedness. Anxiety-related items were categorized as obsessions or compulsions and non-anxiety-related items as impulsions. Severity of each reported item was assessed with respect to time per day consumed and amount of distress and interference induced by the item. Following these criteria, each reported item was classified as a symptom, a subthreshold symptom, or just as being present. RESULTS: Across the study groups, obsessions were experienced as more severe than (Tourette-related) impulsions and compulsions. Within the study groups, patients with both Tourette's disorder and OCD reported more symptomatic Tourette-related impulsions, such as mental play, echophenomena, and impulsive or self-injurious behaviors; less overall symptomatic obsessions; and less symptomatic washing than patients with OCD (no tics). The differences among individuals with Tourette's with or without OCD reflected differences in symptom severity rather than differences in symptom distribution. CONCLUSION: Obsessions are more time consuming, distressing, and interfering than compulsions and impulsions. Furthermore, the symptomatic repetitive behaviors were distributed differently among patients with both Tourette's disorder and OCD and patients with OCD (no tics). Patients with Tourette's and OCD are phenomenologically more similar to Tourette's than to OCD. These differences possibly represent differences in underlying pathophysiology between Tourette's and tic-free OCD.     

Health concerns in patients with obsessive-compulsive disorder

In the present study, individuals with obsessive-compulsive disorder (OCD) who also had excessive health concerns (n = 56) were compared with OCD individuals without such concerns (n = 343) regarding their OCD symptom severity, types of obsessions and compulsions, insight into the irrationality of their obsessions, and prevalence of generalized anxiety disorder. While the presence of health concerns did not affect the severity of OCD symptoms, the groups differed with respect to the types of symptoms displayed: those with health concerns had more somatic and harm obsessions, and checking compulsions: whereas those without such concerns had more contamination obsessions and washing compulsions. The insight of both groups ranged from poor to excellent, yet the number of individuals with poor insight was greater among those with health concerns than those without. Generalized anxiety disorder was also more prevalent among OCD individuals with excessive health concerns.     

The Relationship Between Anxiety and Repetitive Behaviours in Autism Spectrum Disorder

Children with Autism Spectrum Disorder are vulnerable to anxiety. Repetitive behaviours are a core feature of Autism Spectrum Disorder (ASD) and have been associated anxiety. This study examined repetitive behaviours and anxiety in two groups of children with autism spectrum disorder, those with high anxiety and those with lower levels of anxiety. Children with high anxiety had more repetitive behaviours than those without anxiety. Within the anxiety sample, higher levels of insistence on sameness were associated with more anxiety. No association was found between sensory motor repetitive behaviours and anxiety in this group. In the non-anxious sample, anxiety was associated with sensory motor repetitive behaviours. These findings indicate a differential relationship for repetitive behaviours in relation to anxious and non-anxious children with ASD.     

Recognition and treatment of obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is prevalent, chronic, and potentially disabling. It is characterized by recurrent, unwanted, and distressing thoughts (obsessions) and repetitive, irresistible, behaviors (compulsions). Individuals with OCD recognize that the obsessions and compulsions are senseless or excessive yet they are unable to stop these behaviors. Some etiologic theories of OCD suggest a biological origin, including hypotheses involving the serotonergic system, the glutamatergic system, the orbital cortex and the basal ganglia, and streptococcal throat infections in children. Standard treatments for OCD include selective serotonin reuptake inhibitors (SSRIs) and cognitive-behavior therapy. Combining SSRIs with other medications has relatively little empirical support; however, the adjunctive use of antipsychotics has been shown to be effective. Neurosurgery, such as deep brain stimulation, has also been shown to be effective in select patients with debilitating and refractory OCD.     

Differential diagnosis of obsessive-compulsive symptoms from delusions in schizophrenia: A phenomenological approach

Several studies suggest increased prevalence-rates of obsessive-compulsive symptoms (OCS) and even of obsessive-compulsive disorder (OCD) in patients with schizophrenic disorders. Moreover, it has been recently proposed the existence of a distinct diagnostic sub-group of schizo-obsessive disorder. However, the further investigation of the OCS or OCD-schizophrenia diagnostic comorbidity presupposes the accurate clinical differential diagnosis of obsessions and compulsions from delusions and repetitive delusional behaviours, respectively. In turn, this could be facilitated by a careful comparative examination of the phenomenological features of typical obsessions/compulsions and delusions/repetitive delusional behaviours, respectively. This was precisely the primary aim of the present investigation. Our examination included seven features of obsessions/delusions (source of origin and sense of ownership of the thought, conviction, consistency with one’s belief-system, awareness of its inaccuracy, awareness of its symptomatic nature, resistance, and emotional impact) and five features of repetitive behaviours (aim of repetitive behaviours, awareness of their inappropriateness, awareness of their symptomatic nature, and their immediate effect on underlying thought, and their emotional impact). Several of these clinical features, if properly and empathically investigated, can help discriminate obsessions and compulsive rituals from delusions and delusional repetitive behaviours, respectively, in patients with schizophrenic disorders. We comment on the results of our examination as well as on those of another recent similar investigation. Moreover, we also address several still controversial issues, such as the nature of insight, the diagnostic status of poor insight in OCD, the conceptualization and differential diagnosis of compulsions from other categories of repetitive behaviours, as well as the diagnostic weight assigned to compulsions in contemporary psychiatric diagnostic systems. We stress the importance of the feature of mental reflexivity for understanding the nature of insight and the ambiguous diagnostic status of poor insight in OCD which may be either a marker of the chronicity of obsessions, or a marker of their delusionality. Furthermore, we criticize two major shortcomings of contemporary psychiatric diagnostic systems (DSM-IV, DSM-V, ICD-10) in their criteria or guidelines for the diagnosis of OCD or OCS: first, the diagnostic parity between obsessions and compulsions and, second, the inadequate conceptualization of compulsions. We argue that these shortcomings might artificially inflate the clinical prevalence of OC symptoms in the course of schizophrenic disorders. Still, contrary to a recent proposal, we do not exclude on purely a priori grounds the possibility of a concurrence of genuine obsessions along with delusions in patients with schizophrenia.     

Variations in Symptom Prevalence and Clinical Correlates in Younger Versus Older Youth with Obsessive–Compulsive Disorder

Few studies have examined the phenomenology of obsessive–compulsive disorder (OCD) in younger children. A sample of 292 treatment seeking youth with a primary diagnosis of OCD was divided into the young child (3–9 years old) and older child (10–18 years old) groups. Overall OCD severity did not differ between groups. However, older youth demonstrated stronger intensity of obsessive and compulsive symptoms, while younger children were rated as having less resistance and control of compulsions. Older youth exhibited increased occurrence of comorbid depression, and an increased occurrence of sexual, magical thinking, and somatic obsessions, as well as, checking, counting and magical thinking compulsions. Conversely, the group of younger children exhibited significantly poorer insight, increased incidence of hoarding compulsions, higher rates of comorbid attention deficit/hyperactivity disorder, disruptive behavior, and parent-rated anxiety, and more frequently exhibited hoarding compulsions. These differences suggest domains to consider when screening for OCD among younger/older pediatric cohorts.     

Phenotypic differences in early- and late-onset obsessive-compulsive disorder

Early-onset forms of many medical diseases have been associated with specific genetic anomalies. To assess the potential marker value of onset age in obsessive-compulsive disorder (OCD), we examined and compared the phenotypic characteristics of patients with early and later onset. The study sample included 38 children with DSM-IV OCD and 129 adults 19 years of age or older, 77 of whom reported OCD onset prior to age 18 and 52 of whom reported OCD onset at 18 years of age or older. DSM-IV diagnoses were ascertained for all subjects using an amended version of the Diagnostic Interview for Genetic Studies (DIGS). An initial comparison of children and adults with childhood onset revealed several differences, including an earlier onset of clinically significant symptoms without impairment and earlier onset of DSM-IV OCD, a higher frequency of learning disabilities, and fewer obsessions and compulsions among our child patients. For this reason, subsequent analyses included only adult patients with early and later OCD onset. Nonimpairing symptom onset prior to puberty, a relatively aggressive course, and a greater number of obsessions and compulsions unrelated to the amount of time in illness characterized early-onset OCD. Later-onset OCD was characterized by nonimpairing symptom onset during puberty, a static course, and relatively few obsessions and compulsions that were variably related to the amount of time in illness. We conclude that children with OCD and adults with childhood onset differ in their report of clinical characteristics and should be analyzed separately in studies concerning the phenotypic characteristics of OCD. Early- and late-onset forms of OCD appear to be characterized by phenotypic features that have important neurobiologic and perhaps genetic implications.     

Influence of age of onset on clinical features in obsessive-compulsive disorder

We compared early-onset and late-onset obsessive-compulsive disorder (OCD) patients in terms of demographic and clinical features. One hundred sixteen outpatients whose primary diagnosis was OCD according to DSM-IV diagnostic criteria were recruited. Early-onset (n=50) and late-onset (n=66) OCD groups were compared with respect to demographic variables and scores obtained on various scales. A male gender predominance was found in early-onset OCD group. Symmetry/exactness obsessions, religious obsessions, hoarding/saving obsessions, and hoarding/collecting compulsions also were significantly more frequent in the early-onset group than in the late-onset group. The results may suggest a phenotypic difference between the two groups. Further studies are needed to investigate the differences between early-onset and late-onset OCD groups to examine the hypothesis that early-onset OCD is a distinct subtype of the disorder.     

Obsessive–compulsive traits in children and adolescents with Asperger syndrome

The objective of this study is to examine the occurrence and characteristic features of obsessive–compulsive behaviours in children and adolescents with Asperger syndrome (AS), with respect to a matched obsessive compulsive disorder group (OCD) and a typically developing control group (CG). For this purpose, 60 subjects (20 OCD; 18 AS; 22 CG), aged 8–15 years, matched for age, gender and IQ were compared. AS and OCD patients were diagnosed according to the DSM-IV-TR criteria. The Autism Diagnostic Interview-Revised and the Autism Diagnostic Observation Schedule were used to assist in the AS diagnosis; the WISC-R was administered to assess IQ. Obsessive and compulsive symptoms were evaluated by using the Children’s Yale-Brown Obsessive-Compulsive Scale (CY-BOCS). None of the AS children received a formal diagnosis of OCD. The AS group presented significantly higher frequencies of Hoarding obsessions and Repeating, Ordering and Hoarding compulsions compared to CG. The OCD group, in turn, reported significantly higher frequencies of Contamination and Aggressive obsessions and Checking compulsions compared to both the AS group and CG. As expected, the OCD group displayed a higher severity of symptoms (Moderate level of severity) than did the AS group (Mild level of severity). Finally, in our sample, neither the OCD group nor the AS group demonstrated a completely full awareness of the intrusive, unreasonable and distressing nature of symptoms, and the level of insight did not differ between the OCD group and CG, although an absence of insight was observed in the AS group. Children with AS showed higher frequencies of obsessive and compulsive symptoms than did typically developing children, and these features seem to cluster around Hoarding behaviours. Additionally, different patterns of symptoms emerged between the OCD and AS groups. Finally, in our sample, the level of insight was poor in both the OCD and the AS children. Further research should be conducted to better understand the characteristics of repetitive thoughts and behaviours in autism spectrum disorders, and to clarify the underlying neurobiological basis of these symptoms.     

Symptom subtypes of obsessive-compulsive disorder: are they relevant for treatment?

Several symptom subtypes of obsessive-compulsive disorder (OCD) have been identified on the basis of the predominant obsessions and compulsions. The objectives of the present article were to review the literature on the relationship between OCD symptom subtypes and treatment response and to suggest strategies that might assist with the choice of treatment and improve treatment outcome in patients with various subtypes. An extensive literature search was performed, relevant studies were identified, and their results reported. Overt compulsions were generally associated with a relatively good response to the behaviour therapy technique of exposure and response prevention (ERP) and with poorer response to serotonin re-uptake inhibitors (SRIs). Washing/cleaning and checking compulsions tend to respond well to ERP, whereas the majority of studies show that washing/cleaning compulsions are associated with a poorer response to SRIs. Most studies suggest that patients with the symmetry, ordering and arranging subtype do not fare worse with ERP and SRIs than patients with other symptom subtypes. Some studies suggested that obsessions might respond to SRIs somewhat better than to ERP. In the majority of the studies, hoarding and the subtype characterized by sexual or religious obsessions and absence of overt compulsions ('pure obsessions') have been associated with poor response to ERP and SRIs. It was concluded that treatment strategies cannot be precisely tailored to OCD symptom subtypes. Many other factors influence the outcome of treatment and need to be considered along with the symptom subtypes when making decisions about treatment. While ERP and SRIs remain the mainstay of treatment regardless of the symptom subtype, the addition of cognitive therapy techniques and/or antipsychotic medications may enhance treatment response in the presence of certain features discussed in the article.     

OCD symptoms in a sample of Turkish patients: a phenomenological picture

This study aimed to investigate the clinical features of obsessive-compulsive disorder (OCD) and the possible association between obsessive-compulsive symptoms and culture-related characteristics in a sample of Turkish patients with OCD. We studied 141 patients with OCD (according to DSM-IV criteria) consecutively admitted to our outpatient clinic during the period from February 1998 to December 2003. We used the Turkish version of the Structured Clinical Interview for DSM-IV (SCID) to interview all patients, and the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) to assess obsessive-compulsive symptoms and severity. The onset of OCD symptoms was earlier in males. Major depression was the most common comorbid disorder (30.5%). The most commonly occurring obsessions were contamination (56.7%), aggression (48.9%), and somatic (24.1%), followed by religious (19.9%), symmetry (18.4%), and sexual imagery (15.6%). Symmetry and sexual obsessions, and checking compulsions and rituals, tended to be more common in male patients. Dirt and contamination obsessions and washing compulsions were slightly more common in females. The vast majority of patients with religious obsessions (83%) and half of the patients with sexual obsessions had compulsions that included religious practices. Also, patients with sexual and religious obsessions had delayed seeking professional help.     

Obsessive—compulsive disorder in childhood

Twenty children who met DSM-III-R criteria for obsessive-compulsive disorder (OCD) were identified among 190 consecutive referrals to an anxiety clinic for children and adolescents. Children and their families were assessed directly for lifetime psychopathology with structured diagnostic interviews, at which time sociodemographic data also were collected. Results indicated that clinically referred childhood OCD is more common among boys, and that boys have an earlier age-at-onset than their female counterparts. As true for adult patients with the disorder, obsessions without compulsions were relatively rare, multiple rituals were common, and the most common compulsive ritual was washing. Comorbid anxiety disorders were common among the children, but depressive disorders were rare. Examination of the psychiatric histories of the first- degree relatives (mothers, fathers, siblings) yielded a prevalence rate of 7.7% for OCD; thus, we did not obtain strong support for the notion that the disorder aggregates within families. Findings from this study provide independent confirmation of results previously obtained from the NIMH cohort of OCD children.     

Obsessive-compulsive disorder with and without tics in a clinical sample of children and adolescents

The purpose of this study was to discriminate subtypes of obsessive-compulsive disorder (OCD) in a clinical sample of children and adolescents. Sixty OCD patients were assessed in two outpatient psychiatric clinics; 15 patients had a lifetime history of tics and 45 patients had no tic history. Interviews were conducted with the patients and their parents by a child psychiatrist using the Children's Yale-Brown Obsessive Compulsive Scale (CY-BOCS). The symptom checklist of the CY-BOCS was used to categorize obsessions and compulsions. Discriminant function analysis was used to compare the two groups in their symptomatology. There was no difference between the two groups in seven obsession categories. However, there was a significant difference between the two groups in seven compulsion categories. Ordering, hoarding, and washing compulsions were more common in those with no tic history. The results indicate that tic-related OCD may be differentiated from non-tic-related OCD early in life by the presence or absence of certain compulsive symptoms.     

Obsessive-compulsive disorder in youth with and without a chronic tic disorder

The goal of this study was to discriminate subtypes of pediatric obsessive-compulsive disorder (OCD) among youth with and without a comorbid tic disorder. Seventy-four youth (M(age)=9.7+/-2.3 years) with a principal diagnosis of OCD, with (n=46) or without (n=28) a comorbid tic disorder, were assessed with a semi-structured diagnostic interview and the Children's Yale Brown Obsessive-Compulsive Scale (CY-BOCS). The CY-BOCS Symptom Checklist was used to categorize obsessions and compulsions. Group differences were analyzed by t tests, chi(2), and discriminant function analyses. Results suggested that subjects without tics had significantly more contamination obsessions, sexual obsessions, and counting compulsions than youth with comorbid tics. Generally speaking, however, youth with and without tics had similar symptom presentations. These data suggest that pediatric OCD patients with and without comorbid tics may have some aspects of symptom presentation that differ, but generally have more OCD symptoms in common than different. Implications of these findings on clinical presentation and treatment efficacy are highlighted.     

Phenomenology of OCD: Lessons from a large multicenter study and implications for ICD-11

This study aimed to investigate the phenomenology of obsessive–compulsive disorder (OCD), addressing specific questions about the nature of obsessions and compulsions, and to contribute to the World Health Organization's (WHO) revision of OCD diagnostic guidelines. Data from 1001 patients from the Brazilian Research Consortium on Obsessive–Compulsive Spectrum Disorders were used. Patients were evaluated by trained clinicians using validated instruments, including the Dimensional Yale–Brown Obsessive–Compulsive Scale, the University of Sao Paulo Sensory Phenomena Scale, and the Brown Assessment of Beliefs Scale. The aims were to compare the types of sensory phenomena (SP, subjective experiences that precede or accompany compulsions) in OCD patients with and without tic disorders and to determine the frequency of mental compulsions, the co-occurrence of obsessions and compulsions, and the range of insight. SP were common in the whole sample, but patients with tic disorders were more likely to have physical sensations and urges only. Mental compulsions occurred in the majority of OCD patients. It was extremely rare for OCD patients to have obsessions without compulsions. A wide range of insight into OCD beliefs was observed, with a small subset presenting no insight. The data generated from this large sample will help practicing clinicians appreciate the full range of OCD symptoms and confirm prior studies in smaller samples the degree to which insight varies. These findings also support specific revisions to the WHO's diagnostic guidelines for OCD, such as describing sensory phenomena, mental compulsions and level of insight, so that the world-wide recognition of this disabling disorder is increased.     

Religiosity and religious obsessions in obsessive-compulsive disorder.

Religion has often been thought to play a part in the genesis of some cases of obsessive-compulsive disorder (OCD). In this study, we explored the relationship between religiosity, religious obsessions, and other clinical characteristics of OCD. Forty-five outpatients with OCD were evaluated with the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) and the Yale-Brown Obsessive-Compulsive Checklist (Y-BOCC) as well as the Religious Practices Index (RPI), which was developed for this study. On the basis of these evaluations, 42% of the patients were found to have religious obsessions. Despite differences in the frequency of religious obsessions found in this study compared with others, a factor analysis revealed the symptom dimensions to be similar to those found in other OCD samples. There was no significant difference in the overall severity of obsessions and compulsions between patients with and without religious obsessions. RPI scores did not differ significantly between groups. We failed to find a relationship between RPI scores or religious obsessions and any particular type of obsession or compulsion. A logistic regression analysis revealed that the sole predictor of the presence of religious obsessions was a higher number of types of obsessions. In conclusion, we failed to find a conclusive relationship between religiosity and any other clinical feature of OCD, including the presence of religious obsessions. On the other hand, we showed that the patients who tend to have a variety of obsessions are more likely also to have religious obsessions. Thus, religion appears to be one more arena where OCD expresses itself, rather than being a determinant of the disorder.     

Acute onset and remission of obsessions and compulsions following medical illnesses and stress

Obsessive Compulsive Disorder (OCD) is generally chronic. Episodic OCD with complete remission has been rarely reported. Two cases of brief, episodic obsessions and compulsions that appeared for the first time following psychological stress and in the context of medical illness are reported. The possibility of brief episodes of OCD precipitated by stress is illustrated. Exploration of this phenomenon may help us learn more about OCD in general.     

Quality of life in obsessive-compulsive disorder: the different impact of obsessions and compulsions

BACKGROUND: Patients with obsessive-compulsive disorder (OCD) are troubled by repeated obsessions and/or compulsions, which seem senseless and frequently repugnant. OBJECTIVE: The study examines the differential impact of obsessions and compulsions on the quality of life (QoL) of patients with OCD. METHODS: Seventy-five patients (43 females, 32 males) between 21 and 62 years old with OCD (ICD 10 F42.0-F42.2) were recruited from the outpatient clinic for anxiety disorders at the Department of Psychiatry of the University of Leipzig. The severity of OCD symptoms was assessed by the Yale Brown Obsessive-Compulsive Scale (a standardized, clinician-administered scale), and depressiveness was assessed with the Beck Depression Inventory (a self-report instrument). QoL was assessed by means of the WHOQOL-BREF, a self-administered questionnaire developed by WHO. RESULTS: Compulsions reduced patients' QoL in the WHOQOL-BREF domains 'physical well-being', 'psychological well-being' and 'environment', whereas obsessions did not have any impact on QoL ratings. Depressive symptoms were a strong predictor of poor QoL in OCD patients. CONCLUSIONS: In order to judge the QoL of OCD patients, obsessions and compulsions have to be considered differently. Diagnosing and treating depressive symptoms is important for improving the QoL in OCD.     

Neuroendocrine and behavioral responses to challenge with the indirect serotonin agonist dl-fenfluramine in adults with obsessive-compulsive disorder.

Neuroendocrine and behavioral responses to a single 60-mg oral dose of the indirect serotonin agonist dl-fenfluramine were assessed in unmedicated adults with obsessive-compulsive disorder (OCD) and neuroendocrine results contrasted with those in normal control subjects. Net fenfluramine-induced prolactin release did not differ significantly between OCD patients and normal controls. Prolactin responses in the OCD group were not significantly correlated with baseline Yale-Brown Obsessive Compulsive Scale scores for either obsessions or compulsions, but were positively correlated with the baseline Hamilton Depression Scale score and Hamilton Anxiety Scale score. No clear difference in the severity of patients' obsessions or compulsions was found following challenge with fenfluramine versus placebo. Although the present study does not demonstrate a serotonergic abnormality in OCD, this may be more a reflection of limitations of the test procedures than evidence that central nervous system (CNS) serotonergic function is normal in the disorder.