Distinctly different patterns of cognitive deficits are found between schizophrenia and nonpsychotic major depressive disorder, Dr. Shuo-En Hsu and associates reported.

They compared 30 drug-naive participants with schizophrenia, 30 with drug-naive nonpsychotic major depressive disorder (MDD), and 30 matched controls. People with schizophrenia scored significantly worse on the Wisconsin Card Sorting Test than those from the MDD group or the controls, making an average of 17 perseveration errors, about 50% more than the other groups, whose WCST scores were comparable. Patients in both the schizophrenia and MDD groups scored significantly worse than the control group on the Continuous Performance Test, said Dr. Hsu of the department of psychiatry at National Cheng Kung University Hospital in Tainan, Taiwan, and associates.

In contrast to the WCST, patients with MDD performed significantly worse on the Finger Tapping Test than did the schizophrenia or the control-group patients. Schizophrenia patients scored slightly worse than those in the control group, with an average score of about 43, compared with 47 in the control group and 38 in the MDD group.

“Further studies may focus on the qualitative differences between less heterogeneous patient groups; for example, drug-naive patients with schizophrenia and psychotic depression,” the investigators concluded.

Find the full study in the Journal of Affective Disorders (2015;175:133-8 doi:10.1016/j.jad.2014.12.059).



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