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Title: The neuropsychology of impulsivity and cognitive flexibility
Author: Chamberlain, S. R.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2007
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Despite the theoretical and clinical importance of the terms impulsivity and cognitive flexibility, there has been relatively little research in humans setting to (i) to fractionate these terms neuropsychologically using objective computerised tests; (ii) to investigate the relationship between impairments in these domains and the manifestation of psychiatric symptoms; and (iii) to investigate the neurochemical substrates of these functions. The first half of this thesis investigates impulsivity and cognitive flexibility in Obsessive Compulsive Disorder (OCD) and trichotillomania (repetitive hair-pulling).  Impaired response inhibition (i.e. increased motor impulsivity) was found in both OCD and trichotillomania patients, but only patients with OCD exhibited cognitive inflexibility across several tasks. Following up these studies, motor impulsivity and cognitive inflexibility were identified in unaffected first-degree relatives of OCD patients, suggesting that these deficits represent trait rather than state impairments that can exist in the absence of medication confounds and clinical phenotype. The second half of this thesis investigates the neurochemical substrates of impulsivity and cognitive flexibility by using single-dose pharmacological manipulations in healthy volunteers and in neuropsychiatric patients. A double-dissociation is observed for the involvement of noradrenaline and serotonin in response inhibition and probabilistic learning in healthy volunteers. Inhibition of noradrenaline reuptake (with atomoxetine) improved response inhibition with no effect on probabilistic learning with no effect on response inhibition. Agonism of serotonin 1A receptors (with buspirone) had no effect on response inhibition in healthy volunteers. Atomoxetine was also shown to improve aspects of impulse control in adult patients with ADHD.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available