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Title: Cognition during the lifecourse in psychosis
Author: Barnett, J. H.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2006
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This thesis aimed to characterise cognitive function during the lifecourse of patients with psychotic disorders and children from the general population. Cognitive change over one year was assessed in two psychotic samples: one, a mixed sample of patents presenting to a specialist first-episode psychosis (FEP) service, the other a group of patients with established schizophrenia taking part in a drug trial. Patients in FEP showed widespread and heterogeneous cognitive impairment. This heterogeneity was not explained by diagnosis, symptoms or duration of untreated psychosis, or by previous or present substance use. Independent impairments in executive function and associative learning may reflect underlying fronto-striatal and medial temporal pathologies. Some cognitive improvement was found over the first year after initial assessment in both FEP and established schizophrenia. In both samples a general cognitive factor accounted for around 40-50% of the variance in cognition. In established schizophrenia, this general factor affected function outcome and quality of life; its effects were mediated by positive and negative symptom levels. Variants of COMT, a putative risk gene for schizophrenia, affected IQ and executive function in the general population of boys, but not girls, at ages 8 to 10 years. Effects were greater in boys who were entering puberty. Cognitive function in psychotic disorders shows some change over time, but these changes are small compared with the wide variation in cognition between individuals. This variation may reflect underlying genetic and pathological differences, which may interact with normal development during puberty. More studies are needed on the effects in the healthy population of risk genes for schizophrenia. Interventions to treat cognitive impairment in psychosis are needed, both to improve function, and as tools for further research into the process underlying psychosis.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available