Schizophrenia and psychotic depression are two psychiatric disorders sharing in common the presence of psychotic features, delusion, hallucinations or both and severe impairment in occupational functions. Added to that the diagnostic dilemma to differentiate between severe psychomotor retardation, which is not uncommon in psychotic depression, and negative symptoms of schizophrenia. Our work aims at utilizing Wisconsin Card Sorting Test WCST performance as a differentiating diagnostic tool helping in differentiating between both diagnosis.

Patients are recruited randomly from the outpatient service of Alexandria University Hospitals, three groups are included;

Group I patients with psychotic depression,

Group II schizophrenic patients and

Group III control group.

Patients recruited in both group I and II score 4 or higher on the Clinical Global Impression for Severity CGI-S scale, all participants were subjected to Brief Psychiatric Rating scale and Wisconsin Card Sorting Test WCST 128 card computerized version.

The study showed severe impairment in executive functions in all parameters assessed by the WCST including number of administered trials, percentage of errors and perseverative errors as well as failure to maintain categories. Such cognitive dysfunction was significantly more severe in schizophrenia than both other groups. Both schizophrenic and psychotically depressed groups showed poorer performance compared to healthy control.

Performance on WCST may be of great help as a differentiating diagnostic tool to distinguish between schizophrenia and psychotic depression.