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Differential working memory impairment in bipolar disorder and schizophrenia: effects of lifetime history of psychosis
Author(s) -
Glahn David C,
Bearden Carrie E,
Cakir Sibel,
Barrett Jennifer A,
Najt Pablo,
Serap Monkul E,
Maples Natalie,
Velligan Dawn I,
Soares Jair C
Publication year - 2006
Publication title -
bipolar disorders
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.285
H-Index - 129
eISSN - 1399-5618
pISSN - 1398-5647
DOI - 10.1111/j.1399-5618.2006.00296.x
Subject(s) - schizoaffective disorder , bipolar disorder , schizophrenia (object oriented programming) , psychosis , psychology , working memory , neuropsychology , psychiatry , cognition
Background: Although bipolar disorder and schizophrenia have long been viewed as distinct illnesses, there is growing evidence that these two complex diseases share some common genes, which may manifest as overlapping neuropsychological impairments. Although working memory dysfunction has been proposed to be central to the pathophysiology of schizophrenia, it has received less attention in studies of bipolar disorder. Method: We applied measures of working memory to patients with schizophrenia (n = 15), patients with schizoaffective disorder (n = 15), patients with psychotic (n = 11) and non‐psychotic (n = 15) bipolar disorder, and demographically matched healthy subjects (n = 32), in order to determine the extent to which these groups show common or unique impairments. Results: While patients with bipolar disorder (with and without psychotic features) and those with schizophrenia/schizoaffective disorder were impaired on backward digit span, only patients with a lifetime history of psychotic features, regardless of diagnosis, were impaired on spatial delayed response task. Conclusions: Backward digit span performance is comparable in bipolar disorder and schizophrenia, and may be an appropriate endophenotypic marker that cuts across diagnostic categories. In contrast, spatial working memory performance clearly distinguishes non‐psychotic bipolar disorder patients from patients with functional psychosis.