Get access

Differential working memory impairment in bipolar disorder and schizophrenia: effects of lifetime history of psychosis

Authors

  • David C Glahn,

    1. Division of Schizophrenia and Related Disorders, Department of Psychiatry, The University of Texas Health Science Center at San Antonio, San Antonio, TX
    Search for more papers by this author
  • Carrie E Bearden,

    1. Department of Psychiatry & Biobehavioral Sciences, University of California, Los Angeles, CA
    Search for more papers by this author
  • Sibel Cakir,

    1. Division of Schizophrenia and Related Disorders, Department of Psychiatry, The University of Texas Health Science Center at San Antonio, San Antonio, TX
    Search for more papers by this author
  • Jennifer A Barrett,

    1. Division of Schizophrenia and Related Disorders, Department of Psychiatry, The University of Texas Health Science Center at San Antonio, San Antonio, TX
    Search for more papers by this author
  • Pablo Najt,

    1. Division of Mood and Anxiety Disorders, Department of Psychiatry, The University of Texas Health Science Center at San Antonio
    2. South Texas Veterans Health Care System, Audie L. Murphy Division, San Antonio, TX, USA
    Search for more papers by this author
  • E Serap Monkul,

    1. Department of Psychiatry, Dokuz Eylul University School of Medicine, Izmir, Turkey
    Search for more papers by this author
  • Natalie Maples,

    1. Division of Schizophrenia and Related Disorders, Department of Psychiatry, The University of Texas Health Science Center at San Antonio, San Antonio, TX
    Search for more papers by this author
  • Dawn I Velligan,

    1. Division of Schizophrenia and Related Disorders, Department of Psychiatry, The University of Texas Health Science Center at San Antonio, San Antonio, TX
    Search for more papers by this author
  • Jair C Soares

    1. Division of Mood and Anxiety Disorders, Department of Psychiatry, The University of Texas Health Science Center at San Antonio
    2. South Texas Veterans Health Care System, Audie L. Murphy Division, San Antonio, TX, USA
    Search for more papers by this author

  • The authors of this paper do not have any commercial associations that might pose a conflict of interest in connection with this manuscript.

David C Glahn, PhD, Department of Psychiatry, The University of Texas Health Science Center at San Antonio, Mail Code 7792, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA. Fax: (210) 567-1291;
e-mail: glahn@uthscsa.edu

Abstract

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.

Ancillary