A neuropsychological comparison of obsessive–compulsive disorder and trichotillomania
Introduction
Obsessive–compulsive disorder (OCD) and trichotillomania (repetitive hair-pulling) are debilitating conditions with lifetime prevalence estimated to be 2–3% (Robins et al., 1984) and 0.6% (Christenson, Pyle, & Mitchell, 1991), respectively. OCD is currently classified as an anxiety disorder (DSM-IV, 1994) and is characterised by recurrent intrusive thoughts (obsessions) and/or repetitive mental or behavioural rituals performed in response to obsessions or according to rigid rules (compulsions). Trichotillomania is characterised by repetitive hair-pulling that leads to significant social impairment, and is currently classified as an impulse control disorder (DSM-IV, 1994). However, this classification may be problematic, given the association between trichotillomania and compulsive self-injurious symptoms such as skin picking (Lochner et al., 2005). OCD and trichotillomania share overlapping co-morbidity, familial transmission, and possibly treatment response (Hollander & Rosen, 2000; Stein, Simeon, Cohen, & Hollander, 1995). Phenomenologically, both are characterised by difficulties suppressing inappropriate repetitive behaviours, suggesting underlying dysregulation in inhibitory control processes (Chamberlain, Blackwell, Fineberg, Robbins, & Sahakian, 2005). However, whereas hair-pulling is a relatively simplistic behaviour, rituals in OCD are often complex and performed in response to obsessional thoughts or according to rigid rules (DSM-IV, 1994). Thus, while both OCD and trichotillomania may share overlapping difficulty inhibiting motor behaviour, problems with higher level rigidity may be restricted to OCD alone (Chamberlain, Blackwell, Fineberg, Robbins, & Sahakian, 2006b).
Many studies have examined neuropsychological functioning in OCD, but relatively little research has been conducted in trichotillomania. Deficits in OCD have been reported on tests of executive planning, strategy implementation, and memory (reviewed in, e.g. Chamberlain et al., 2005; Fontenelle, Mendlowicz, Paulo, & Marcio, 2006; Kuelz, Hohagen, & Voderholzer, 2004). For trichotillomania, case–control studies find some support for deficits on tests of memory, executive function, and divided attention (Coetzer & Stein, 1999; Keuthen et al., 1996; Stanley, Hannay, & Breckenridge, 1997). Very few studies have attempted to compare cognition in OCD and trichotillomania directly. Of the handful of available studies, two found tentative support for an overlapping visuo-spatial memory deficit (Coetzer & Stein, 1999; Rettew, Cheslow, & Rapoport, 1991), and another found evidence for differential impairments on the object alternation test (impaired in trichotillomania) and the Wisconsin card sorting test (impaired in OCD) (Bohne et al., 2005). Existing studies have frequently included patients with co-morbidities (especially, depression and other anxiety disorders), which likely contributed to the cognitive findings, and have assessed a relatively narrow range of neuropsychological function.
In recent years, theoretically driven computerized tests have been developed that are capable of tapping separable cognitive domains dependent upon fronto-striatal circuitry (Chamberlain & Sahakian, 2005). Modern models of OCD neuropathology posit abnormalities in fronto-striatal circuitry (especially anterior cingulate cortex, orbitofrontal cortex, and basal ganglia) (Chamberlain et al., 2005; Graybiel & Rauch, 2000). Whether or not similar neural circuitry is implicated in trichotillomania is unclear. The present study sought to compare performance of axis-I co-morbidity-free OCD and trichotillomania patients using a battery of tests targeted on likely areas of impairment. We included core tests of cortico-subcortical integrity from the Cambridge Neuropsychological Test Automated Battery (CANTAB), including visual Pattern Recognition Memory, Spatial Working Memory, and the Tower of London (http://www.camcog.com). Given the recent interest in impulsivity in the context of these disorders (Chamberlain et al., 2005), we also included a test of the tendency to gather and evaluate information prior to making a decision (‘reflection-impulsivity’) (Clark, Robbins, Ersche, & Sahakian, 2006). As decision-making had yet to be assessed in trichotillomania, we also included the Cambridge gamble task, which has been linked to orbitofrontal cortex function (Murphy et al., 2001; Rahman, Sahakian, Hodges, Rogers, & Robbins, 1999; Rogers, Everitt et al., 1999). The probabilistic learning and reversal test was included, which is also thought to be sensitive to orbitofrontal cortex function (Clark, Cools, & Robbins, 2004; Evers et al., 2005; Fellows & Farah, 2003). Finally, the affective go/no-go test was also incorporated into the battery. This test is sensitive to affective processing abnormalities in mood disorders (Erickson et al., 2005, Murphy et al., 1999).
Given that the symptoms of OCD but not trichotillomania suggest problems with high-level cognitive rigidity, it was hypothesized that OCD patients would show cognitive deficits across a broader range of domains than for trichotillomania. In previous work we identified overlapping motor impulsivity, as indexed by the stop-signal paradigm, in these two disorders (Chamberlain et al., 2006b). Therefore, it was hypothesized that OCD and trichotillomania might also share overlap in another type of impulsivity: reflection-impulsivity, which refers to the pre-decisional aspect of behavioural regulation where information is gathered and evaluated prior to making a decision. None of the cognitive tests in the present study had been evaluated in trichotillomania patients previously, to our knowledge. While neurocognitive findings in OCD to date are somewhat mixed, at least one prior study found impaired CANTAB Pattern Recognition Memory versus controls (Watkins et al., 2005), and another found impaired Tower of London performance associated with abnormal fronto-striatal dysfunction (van den Heuvel et al., 2005). Therefore, we predicted impaired Pattern Recognition Memory and Tower of London performance in OCD. The Cambridge gamble task, along with the probabilistic learning task, are thought to be sensitive to orbitofrontal cortex pathology (Clark et al., 2004). While prior studies have not examined probabilistic learning on OCD, intact performance has been reported on Cambridge Gamble versus controls (Watkins et al., 2005). Therefore, we predicted intact Cambridge gamble and probabilistic learning in OCD. Finally, we predicted that neither clinical group would show a similar mood bias to that previously reported in depressed patients on the Affective go/no-go test, as we were careful to exclude patients with co-morbid mood disorders (see below).
Section snippets
Methods
The study was approved by the Cambridge Local Research Ethics Committee. Patients were recruited via an outpatient mental health centre pool of approximately 200 patients after being screened by a consultant psychiatrist (NF) specializing in obsessive–compulsive spectrum disorders, using extended clinical interview supplemented with the Mini International Neuropsychiatric Interview (MINI) (Sheehan et al., 1998). Patients met DSM-IV criteria for their respective conditions. The MINI screened out
Demographic and clinical characteristics
As can be seen in Table 1, groups did not differ significantly in the ANOVA for age, education, verbal IQ, and mood scores. Total impulsive personality trait scores according to the BIS did not differ significantly between groups. Groups did not differ in terms of male:female ratio (chi-squared analysis). Mean Y-BOCS score in the OCD group was 20.40 (±S.D. 4.07), representing mild–moderate disease severity. In the trichotillomania group, mean MGH score was 13.95 (±4.50), representing
Discussion
To our knowledge, this is the first study to compare a broad range of neuropsychological functions in OCD and trichotillomania patients who were free from axis-I co-morbidities. These two disorders share overlapping phenomenology (repetitive inappropriate motor behaviour), and familial transmission (Fontenelle, Mendlowicz, & Versiani, 2005); Lenane et al., 1992, Lochner et al., 2005, Stanley et al., 1997; Swedo & Leonard, 1992). OCD is associated with abnormalities in fronto-striatal circuitry
Acknowledgements
SRC is supported by a priority research studentship from the Medical Research Council (MRC) and by the School of Clinical Medicine, University of Cambridge. This work was also funded by a Wellcome Trust Programme Grant awarded to TWR, BJ Everitt, AC Roberts and BJS. ADB, TWR, and BJS consult for Cambridge Cognition.
References (74)
- et al.
Decision-making heterogeneity in obsessive–compulsive disorder: Ventromedial prefrontal cortex function predicts different treatment outcomes
Neuropsychologia
(2002) - et al.
The neuropsychology of obsessive compulsive disorder: The importance of failures in cognitive and behavioural inhibition as candidate endophenotypic markers
Neuroscience and Biobehavioral Reviews
(2005) - et al.
The neuropsychology of ventral prefrontal cortex: Decision-making and reversal learning
Brain and Cognition
(2004) - et al.
Reflection impulsivity in current and former substance users
Biological Psychiatry
(2006) - et al.
Toward a neurobiology of obsessive–compulsive disorder
Neuron
(2000) - et al.
Neuropsychological functioning in trichotillomania
Biological Psychiatry
(1996) - et al.
Neuropsychological performance in obsessive–compulsive disorder: A critical review
Biological Psychology
(2004) - et al.
Neuropsychological performance in medicated vs. unmedicated patients with obsessive–compulsive disorder
Psychiatry Research
(2002) - et al.
Impulsive disorders in Japanese adult patients with obsessive–compulsive disorder
Comprehensive Psychiatry
(2005) - et al.
Brain activation of patients with obsessive–compulsive disorder during neuropsychological and symptom provocation tasks before and after symptom improvement: A functional magnetic resonance imaging study
Biological Psychiatry
(2005)
Decision making performance in obsessive compulsive disorder
Journal of Affective Disorders
Visuospatial memory deficits at different stages of Parkinson's disease
Neuropsychologia
Planning and spatial working memory following frontal lobe lesions in man
Neuropsychologia
Neuropsychological test performance in trichotillomania: A further link with obsessivecompulsive disorder
Journal of Anxiety Disorders
Dissociable deficits in the decision-making cognition of chronic amphetamine abusers, opiate abusers, patients with focal damage to prefrontal cortex, and tryptophan-depleted normal volunteers: Evidence for monoaminergic mechanisms
Neuropsychopharmacology
Localized orbitofrontal and subcortical metabolic changes and predictors of response to paroxetine treatment in obsessive–compulsive disorder
Neuropsychopharmacology
The neuropsychology of trichotillomania
Journal of Anxiety Disorders
Probabilistic learning and reversal deficits in patients with Parkinson's disease or frontal or temporal lobe lesions: Possible adverse effects of dopaminergic medication
Neuropsychologia
Trichotillomania. An obsessive compulsive spectrum disorder?
The Psychiatric Clinics of North America
Factor analysis of some psychometric measures of impulsiveness and anxiety
Psychological Reports
Impulsivity, time perception, emotion and reinforcement in patients with orbitofrontal cortex lesions
Brain
Visuospatial abilities, memory, and executive functioning in trichotillomania and obsessive–compulsive disorder
Journal of Clinical and Experimental Neuropsychology
The effect of sertraline on cognitive functions in patients with obsessive–compulsive disorder
Psychiatria Polska
Anova for the behavioral sciences researcher
Strategy implementation in obsessive–compulsive disorder and trichotillomania
Psychological Medicine
Motor inhibition and cognitive flexibility in OCD and trichotillomania
American Journal of Psychiatry
Neurochemical modulation of response inhibition and probabilistic learning in humans
Science
Neuropsychological assessment of mood disorder
Clinical Neuropsychiatry
Estimated lifetime prevalence of trichotillomania in college students
Journal of Clinical Psychiatry
Cognitive inflexibility after prefrontal serotonin depletion
Science
Prefrontal serotonin depletion affects reversal learning but not attentional set shifting
Journal of Neuroscience
Neuropsychological measures in women with obsessive–compulsive disorder and trichotillomania
Psychiatry and Clinical Neurosciences
Diagnostic and statistical manual of mental disorders IV (DSM-IV)
Mood-congruent bias in affective go/no-go performance of unmedicated patients with major depressive disorder
The American Journal of Psychiatry
Serotonergic modulation of prefrontal cortex during negative feedback in probabilistic reversal learning
Neuropsychopharmacology
Ventromedial frontal cortex mediates affective shifting in humans: Evidence from a reversal learning paradigm.
Brain
Cited by (175)
OCD symptoms are related to seeking and relying on external information even in neutral perceptual decisions
2023, Journal of Obsessive-Compulsive and Related DisordersEvidence Accumulation and Neural Correlates of Uncertainty in Obsessive-Compulsive Disorder
2023, Biological Psychiatry: Cognitive Neuroscience and NeuroimagingCompulsive-like Behaviors in Amyloid-β 1-42–Induced Alzheimer's Disease in Mice Are Associated With Hippocampo-cortical Neural Circuit Dysfunction
2023, Biological Psychiatry Global Open ScienceThe global assessment of OCD
2022, Comprehensive PsychiatryPrevalence and gender distribution of trichotillomania: A systematic review and meta-analysis
2022, Journal of Psychiatric Research
- 1
Funded by the MRC/Wellcome Trust.