Comparison of memory function in clinically stable patients with schizophrenia and bipolar disorder

Krishnadas, R. , Moore, B. and Patel, R. (2007) Comparison of memory function in clinically stable patients with schizophrenia and bipolar disorder. Journal of Psychopharmacology, 21(7), A37.

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Abstract

<p>Introduction: Cognitive dysfunction, especially executive function and attention, are established findings in euthymic bipolar disorder (BD) and schizophrenia patients. There is suggestion that memory deficits in BD reflect mood state rather than trait deficits. Attempts linking cognitive deficits to social functioning have met some success in schizophrenia but less so in BD. In this report we compare verbal and visual memory in BD and schizophrenia with that of normal controls and explore links to social functioning.</p> <p>Methods: Three groups of 25 subjects were recruited from the outpatient clinics of BYL Nair Hospital, Mumbai, India. The groups comprised subjects aged 18 to 60 years with schizophrenia (in remission), bipolar disorder (currently euthymic) and normal controls and were matched for age, gender and years of education. Memory was assessed using the PGI Memory Scale (Pershad & Wig, 1988) and the Rey-Osterreith Complex Figure Test (ROCFT). Attention was assessed using Trail Making Test A, serial subtractions and reverse counting. Social functioning was examined using the Indian Disability Evaluation and Assessment Scale, (IDEAS; Rehabilitation Committee of the Indian Psychiatric Society, 2000).</p> <p>Results: Concentration was significantly impaired in schizophrenia and BD. Forward and reverse digit span were significantly reduced in both groups, as were immediate and delayed verbal recall. Memory for similar word pair was comparable among the patients, but patients with schizophrenia had poorer memory for dissimilar pairs. Autobiographical memory for both recent and remote events was unimpaired. Short-term visual retention was reduced in both patient groups, whereas visual recognition was unaffected. Both groups performed less well on the ROCFT, indicating impaired immediate and delayed visual memory. Generally, schizophrenia subjects were more impaired that those with BD. Dysfunction scores, rated 0 (absent) to 3 (marked) derived from raw PGI data to account for educational attainment, were significantly (p<0.01) higher in schizophrenic (2.63 + 0.39) compared to BD (1.83 + 0.45) subjects. In BD, dysfunction scores on 1 minute delayed verbal recall correlated positively with IDEAS scores (rho =0.58, p = 0.003). None of the dysfunction scores correlated with IDEAS scores in schizophrenia.</p> <p>Conclusion: The study found widespread deficits in verbal and visual memory, which may be underpinned by working memory deficits. Impaired retention of visual stimuli accompanied by normal recognition suggests retrieval rather than encoding difficulties. Immediate and 1 minute delayed memory were affected, whereas short and long term autobiographical memory appeared intact. Qualitatively, the deficits in schizophrenia and BD were similar whereas quantitatively deficits in BD were consistently less severe. This may indicate overlapping neuropathology, which in the case of delayed verbal memory correlates with social functioning.</p>

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Krishnadas, Dr Rajeev
Authors: Krishnadas, R., Moore, B., and Patel, R.
Subjects:R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
College/School:College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > Mental Health and Wellbeing
Journal Name:Journal of Psychopharmacology
ISSN:0269-8811
ISSN (Online):1461-7285

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