Neuropsychological test profiles in schizophrenia and non-psychotic depression.

OBJECTIVE: The study examined to what degree schizophrenia is characterized by a neuropsychological (NP) test profile specific in shape and level compared with depression and normal functioning. METHOD: Fifty-three patients with schizophrenia, 45 with non-psychotic depression, and 50 normals were assessed with a comprehensive NP test battery and clinical instruments. NP test scores were factor analyzed into seven composite scores. RESULTS: Schizophrenia patients performed significantly below normals across all seven composite scores, whereas depression patients were impaired in two. Verbal memory was most impaired. Sixty-two percent of schizophrenia patients were moderately or severely impaired, the corresponding figure for depression was 28%. Impairment was moderately associated with IQ level and clinical symptom load in schizophrenia, but not in depression. CONCLUSION: Schizophrenia is characterized by deficits across a wide range of NP functions. Thirty-eight percent of the patients are within normal limits. A mild and limited NP disturbance is apparent in depression.

Cortisol level predicts executive and memory function in depression, symptom level predicts psychomotor speed.

OBJECTIVE: On a group level depression is related to hypercortisolism and to psychomotor retardation, executive dysfunction and memory impairment. However, intra-group heterogeneity is substantial. Why some are impaired while others remain in the normal range, is not clear. The present study aims at discerning the relative contribution of present symptom severity and hypercortisolism to impairment in the three domains of cognition. METHOD: Morning saliva cortisol was measured in 26 subjects with recurrent major depression prior to a neuropsychological examination with tests known to be sensitive to cognitive impairment in depression. RESULTS: Cortisol level correlated with executive dysfunction and post-encoding memory deficits, but not with processing speed. Depression level correlated with processing speed. These patterns remained significant after controlling for confounders through partial correlations. CONCLUSION: The association between cortisol and cognition is not an artifact of psychiatric symptom load. High level of saliva cortisol is associated with aspects of cognition that can be dissociated from psychomotor retardation, which is dependent on symptom load.

General psychopathology is more important for executive functioning than diagnosis.

OBJECTIVE: Impaired executive functioning (EF) has often been reported in patients with major depression or schizophrenia. We hypothesize that the variance in EF is more affected by level of general psychopathology than by diagnosis. METHOD: Forty-three patients with major depression and 47 with schizophrenia were included. EF was measured with Wisconsin Card Sorting Test, Stroop Colour Word Test, Paced Auditory Serial Addition Test, Digits Backwards and Controlled Oral Word Association Test. The level of general psychopathology was measured with Brief Psychiatric Rating Scale - Expanded and Positive and Negative Syndrome Scale, the General psychopathology subscale. RESULTS: The level of general psychopathology predicted more of the variance in EF than diagnosis. In multivariate analyses, the effect of general psychopathology on EF was more robust for adjustment for diagnosis than vice versa. CONCLUSION: Future research on cognitive functioning in psychiatric patients should include level of general psychopathology to avoid overemphasising effects of diagnoses.

Attention profile in schizophrenia compared with depression: differential effects of processing speed, selective attention and vigilance.

OBJECTIVE: The aim of the study is to investigate whether subjects with schizophrenia and major depression display attention deficits for different reasons. METHOD: Subjects with schizophrenia (n = 53), recurrent major depression (n = 50) and normal controls (n = 50) were administered with 11 measures of processing speed, selective attention and vigilance. Indices of basal speed, speeded attention, non-speeded attention and vigilance were computed. RESULTS: Both clinical groups were impaired on all chronometric tests. The schizophrenic subjects were also more impaired on speeded attention compared with basal processing speed. Only the schizophrenics were impaired on the non-speeded measures of selective attention. Compared with the schizophrenics, the depressives showed a decrement in vigilance. CONCLUSION: Reduced performance on attention tests in major depression is because of a non-specific speed reduction and loss of vigilance consistent with lack of effort. In addition to generally impaired processing speed, the schizophrenic subjects exposed a deficit in selective attention, indicating executive dysfunction.