Cognitive impairment in schizophrenia and depression: A comparison of stability and course

ABSTRACT

Cognitive deficits are clinically relevant features in schizophrenia and depression, yet little comparative data on changes in both disorders is available. This study compares cognitive performance of inpatients with schizophrenia (N = 52) and unipolar major depression (N = 67) during psychiatric treatment, assessing performance twice: after admission to hospital (acute) and prior to discharge (postacute) on average seven weeks later. A group of healthy controls was tested at comparable intervals. Data was analyzed using a multivariate linear model. Patients with schizophrenia and depression showed significantly impaired performance compared to healthy controls. On follow-up both patient groups showed improved performance. Contrary to expectation, patients with schizophrenia showed greater improvement in verbal memory, visual memory, and psychomotor speed than depressive patients. Verbal fluency presented as a possible candidate to differentiate between both disorders. Similar profiles of generalized cognitive deficits were observed in both patient-groups on acute and postacute assessment, which might indicate trait-like deficits with persistent functional implications in both disorders. Findings do not support assumptions of greater cognitive impairment in schizophrenia compared to depression. A distinction of the disorders on the grounds of cognitive functioning seems to be less specific than presumed.

KEYWORDS:

• Acute
• cognitive impairment
• depression
• postacute
• schizophrenia
• time-course

Acknowledgment

The authors thank all participants. The research was conducted at the Clinic of Psychiatry and Psychotherapy, Charité, University Medicine Berlin, Berlin, Germany.

Disclosure statement

The authors declare that they have no conflict of interest.

Author contributions

P. Neu was responsible for the conception and design of the study. P. Neu and T. Gooren were responsible for the acquisition of the data. P. Schlattmann, T. Gooren, and P. Neu were responsible for the analysis of data. P. Neu, T. Gooren, P. Schlattmann, and U. Niebuhr were responsible for drafting the manuscript and figures.