Schizophrenia scores highest in cognitive impairment study
31 January 2010
Researchers from the Institute of Psychiatry, King’s College London, have found that sufferers of first-episode psychosis have demonstrated higher levels of deficits in learning, memory, attention and functioning than all others in the wider community. The research is published in the American Journal of Psychiatry this month.
Lead author Jolanta Zanelli, said: 'Many times, patients with psychiatric disorders complain about cognitive impairments. Much research has been done on schizophrenia but not as much on other psychotic disorders. We hoped that this study would help us understand what is abnormal in brain function.'
This is the first such study to compare all psychotic disorders: schizophrenia, bipolar disorder or mania, depressive psychosis, and other psychotic disorders, which include persistent delusional disorders, acute and transient psychotic disorders, other non-organic psychotic disorders, and unspecified non-organic disorders and that the impairment was largely generalised.
Ms Zanelli continues: 'The schizophrenia group presented widespread neuropsychological impairments and performed significantly worse than healthy comparison subjects on most neuropsychological measures. Deficits in patients with bipolar disorder or mania were less pervasive but evident in performance scores on verbal memory and fluency tests.'
The results don’t have immediate implications for diagnosis. However, they are very important for ongoing discussions about the possibility of including cognitive impairment as part of diagnostic criteria for schizophrenia in the ICD-11 and DSM-V as they demonstrate that widespread cognitive impairment is not unique to schizophrenia.
Ms Zanelli concludes: 'This was a very well-controlled study of the well-represented groups of patients. The finding that all psychotic disorders share cognitive impairments may suggest that they are as important as symptoms.'
Researchers will now follow the participants to try to understand the cause of cognitive impairment.
The paper’s authors are Professor Robin Murray, Professor Shitij Kapur and Jolanta Zanelli. ‘Specific and Generalized Neuropsychological Deficits: A Comparison of Patients With Various First-Episode Psychosis Presentations’ can be viewed here: http://ajp.psychiatryonline.org/cgi/content/abstract/167/1/78?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=1&author1=zanelli%2C+&andorexacttitle=and&andorexacttitleabs=and&andorexactfulltext=and&searchid=1&FIRSTINDEX=0&sortspec=relevance&resourcetype=HWCIT.