A neuropsychological comparison of obsessive–compulsive disorder and trichotillomania

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Abstract

Background: Obsessive–compulsive disorder (OCD) and trichotillomania (compulsive hair-pulling) share overlapping co-morbidity, familial transmission, and phenomenology. However, the extent to which these disorders share a common cognitive phenotype has yet to be elucidated using patients without confounding co-morbidities. Aim: To compare neurocognitive functioning in co-morbidity-free patients with OCD and trichotillomania, focusing on domains of learning and memory, executive function, affective processing, reflection-impulsivity and decision-making. Method: Twenty patients with OCD, 20 patients with trichotillomania, and 20 matched controls undertook neuropsychological assessment after meeting stringent inclusion criteria. Results: Groups were matched for age, education, verbal IQ, and gender. The OCD and trichotillomania groups were impaired on spatial working memory. Only OCD patients showed additional impairments on executive planning and visual pattern recognition memory, and missed more responses to sad target words than other groups on an affective go/no-go task. Furthermore, OCD patients failed to modulate their behaviour between conditions on the reflection-impulsivity test, suggestive of cognitive inflexibility. Both clinical groups showed intact decision-making and probabilistic reversal learning. Conclusions: OCD and trichotillomania shared overlapping spatial working memory problems, but neuropsychological dysfunction in OCD spanned additional domains that were intact in trichotillomania. Findings are discussed in relation to likely fronto-striatal neural substrates and future research directions.

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)

  • M.M. Nielen et al.

    Decision making performance in obsessive compulsive disorder

    Journal of Affective Disorders

    (2002)
  • A.M. Owen et al.

    Visuospatial memory deficits at different stages of Parkinson's disease

    Neuropsychologia

    (1993)
  • A.M. Owen et al.

    Planning and spatial working memory following frontal lobe lesions in man

    Neuropsychologia

    (1990)
  • D.C. Rettew et al.

    Neuropsychological test performance in trichotillomania: A further link with obsessivecompulsive disorder

    Journal of Anxiety Disorders

    (1991)
  • R.D. Rogers et al.

    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

    (1999)
  • S. Saxena et al.

    Localized orbitofrontal and subcortical metabolic changes and predictors of response to paroxetine treatment in obsessive–compulsive disorder

    Neuropsychopharmacology

    (1999)
  • M.A. Stanley et al.

    The neuropsychology of trichotillomania

    Journal of Anxiety Disorders

    (1997)
  • R. Swainson et al.

    Probabilistic learning and reversal deficits in patients with Parkinson's disease or frontal or temporal lobe lesions: Possible adverse effects of dopaminergic medication

    Neuropsychologia

    (2000)
  • S.E. Swedo et al.

    Trichotillomania. An obsessive compulsive spectrum disorder?

    The Psychiatric Clinics of North America

    (1992)
  • E.S. Barratt

    Factor analysis of some psychometric measures of impulsiveness and anxiety

    Psychological Reports

    (1965)
  • H.A. Berlin et al.

    Impulsivity, time perception, emotion and reinforcement in patients with orbitofrontal cortex lesions

    Brain

    (2004)
  • A. Bohne et al.

    Visuospatial abilities, memory, and executive functioning in trichotillomania and obsessive–compulsive disorder

    Journal of Clinical and Experimental Neuropsychology

    (2005)
  • A. Borkowska et al.

    The effect of sertraline on cognitive functions in patients with obsessive–compulsive disorder

    Psychiatria Polska

    (2002)
  • R.N. Cardinal et al.

    Anova for the behavioral sciences researcher

    (2006)
  • Chamberlain, S. R., Fineberg, N. A., Menzies, L. A., Blackwell, A. D., Bullmore, E. T., Robbins, T. W., & Sahakian, B....
  • S.R. Chamberlain et al.

    Strategy implementation in obsessive–compulsive disorder and trichotillomania

    Psychological Medicine

    (2006)
  • S.R. Chamberlain et al.

    Motor inhibition and cognitive flexibility in OCD and trichotillomania

    American Journal of Psychiatry

    (2006)
  • S.R. Chamberlain et al.

    Neurochemical modulation of response inhibition and probabilistic learning in humans

    Science

    (2006)
  • S.R. Chamberlain et al.

    Neuropsychological assessment of mood disorder

    Clinical Neuropsychiatry

    (2005)
  • G.A. Christenson et al.

    Estimated lifetime prevalence of trichotillomania in college students

    Journal of Clinical Psychiatry

    (1991)
  • H.F. Clarke et al.

    Cognitive inflexibility after prefrontal serotonin depletion

    Science

    (2004)
  • H.F. Clarke et al.

    Prefrontal serotonin depletion affects reversal learning but not attentional set shifting

    Journal of Neuroscience

    (2005)
  • R. Coetzer et al.

    Neuropsychological measures in women with obsessive–compulsive disorder and trichotillomania

    Psychiatry and Clinical Neurosciences

    (1999)
  • DSM-IV

    Diagnostic and statistical manual of mental disorders IV (DSM-IV)

    (1994)
  • K. Erickson et al.

    Mood-congruent bias in affective go/no-go performance of unmedicated patients with major depressive disorder

    The American Journal of Psychiatry

    (2005)
  • E.A. Evers et al.

    Serotonergic modulation of prefrontal cortex during negative feedback in probabilistic reversal learning

    Neuropsychopharmacology

    (2005)
  • L.K. Fellows et al.

    Ventromedial frontal cortex mediates affective shifting in humans: Evidence from a reversal learning paradigm.

    Brain

    (2003)
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