A comparative study of cognitive deficits in patients with delusional disorder and paranoid schizophrenia

Very few studies have evaluated the neurocognitive functions of patients with persistent delusional disorder.

To study the neurocognitive profile of patients with delusional disorder and compare it with those of patients with paranoid schizophrenia and healthy control subjects.

Attention concentration, executive functions, memory, and IQ were assessed in 20 patients with delusional disorder and were compared with 20 patients with paranoid schizophrenia and 20 healthy controls. All three groups were matched on age, sex, and level of education. The two patient groups were also matched on duration of illness.

In general, patients with delusional disorder performed worst than healthy controls and patients with paranoid schizophrenia performed in between the other two groups. Compared with healthy controls, both patients with delusional disorder and patients with paranoid schizophrenia were significantly impaired on different tests of attention and visual learning and memory. Compared with patients with paranoid schizophrenia, patients with delusional disorder had more impairment different tests of attention, visual learning and memory, verbal working memory, and executive functions.

Patients with delusional disorder exhibit cognitive dysfunctions that are very similar to schizophrenia, but are more severe in intensity. The resemblance of cognitive profiles suggests that the two disorders may have similar etiological basis.