Psychological Medicine



Executive function in Tourette's syndrome and obsessive–compulsive disorder


LAURA H. WATKINS a1, BARBARA J. SAHAKIAN a2c1, MARY M. ROBERTSON a4, DAVID M. VEALE a4, ROBERT D. ROGERS a3a5, KATHRYN M. PICKARD a1, MICHAEL R. F. AITKEN a3 and TREVOR W. ROBBINS a3
a1 MRC Cambridge Centre for Brain Repair, University of Cambridge, Cambridge, UK
a2 Department of Psychiatry, University of Cambridge, Cambridge, UK
a3 Department of Experimental Psychology, University of Cambridge, Cambridge, UK
a4 Department of Psychiatry and Behavioural Sciences, Royal Free and University College School of Medicine, University of London; UK
a5 Department of Psychiatry, University of Oxford, Oxford, UK

Article author query
watkins lh   [PubMed][Google Scholar] 
sahakian bj   [PubMed][Google Scholar] 
robertson mm   [PubMed][Google Scholar] 
veale dm   [PubMed][Google Scholar] 
rogers rd   [PubMed][Google Scholar] 
pickard km   [PubMed][Google Scholar] 
aitken mr   [PubMed][Google Scholar] 
robbins tw   [PubMed][Google Scholar] 

Abstract

Background. Cognitive performance was compared in the genetically and neurobiologically related disorders of Tourette's syndrome (TS) and obsessive–compulsive disorder (OCD), in three domains of executive function: planning, decision-making and inhibitory response control.

Method. Twenty TS patients, twenty OCD patients and a group of age- and IQ-matched normal controls completed psychometric and computerized cognitive tests and psychiatric rating scales. The cognitive tests were well-characterized in terms of their sensitivity to other fronto-striatal disorders, and included pattern and spatial recognition memory, attentional set-shifting, and a Go/No-go set-shifting task, planning, and decision-making.

Results. Compared to controls, OCD patients showed selective deficits in pattern recognition memory and slower responding in both pattern and spatial recognition, impaired extra-dimensional shifting on the set-shifting test and impaired reversal of response set on the Go/No-go test. In contrast, TS patients were impaired in spatial recognition memory, extra-dimensional set-shifting, and decision-making. Neither group was impaired in planning. Direct comparisons between the TS and OCD groups revealed significantly different greater deficits for recognition memory latency and Go/No-go reversal for the OCD group, and quality of decision-making for the TS group.

Conclusions. TS and OCD show both differences (recognition memory, decision-making) and similarities (set-shifting) in selective profiles of cognitive function. Specific set-shifting deficits in the OCD group contrasted with their intact performance on other tests of executive function, such as planning and decision-making, and suggested only limited involvement of frontal lobe dysfunction, possibly consistent with OCD symptomatology.


Correspondence:
c1 Professor Barbara Sahakian, Department of Psychiatry (Box 189), University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK. (Email: jenny.hall@cambsmh.nhs.uk)


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