Deficits in sustained attention in patients with schizophrenia but not with bipolar disorder

Background

The aim of the present study was to investigate sustained attention in remitted patients with bipolar disorder and in patients with schizophrenia, as compared to each other and to normal controls; a secondary aim was to investigate the correlations of different symptom dimensions with performance on sustained attention in patients with schizophrenia and bipolar disorder.

Materials and methods

Participants were 29 (18 men) outpatients with schizophrenia (SZ), 19 (8 men) remitted patients with bipolar disorder I (BP), and 30 (15 men) healthy controls (HC); all groups were matched to each other for age, sex, and level of education. Symptom severity (positive symptoms, negative symptoms, and general psychopathology) of patients with SZ were assessed with the Greek version of the Positive and Negative Syndrome Scale (PANSS); residual affective symptoms of patients with BP were assessed with the Young Mania Rating Scale (YMRS) and the Montgomery-Asberg Depression Rating Scale (MADRS). Sustained attention was measured by means of the Penn Continuous Performance Test (PCPT).

Results

The three groups differed significantly on the PCPT scores. Patients with SZ performed poorer than both patients with BP and HC, whereas patients with BP did not differ significantly from HC. Performance on the PCPT did not significantly correlate with scores on the YMRS and MADRS in patients with BP. Scores on the PCPT did not correlate significantly with scores on any of the three subscales of the PANSS.

Discussion

Outpatients with schizophrenia presented deficits in sustained attention, whereas remitted patients with bipolar disorder I did not manifest such impairment. It seems that impaired sustained attention may be a trait deficit in schizophrenia, but not in bipolar disorder.