Obesity has been associated with cognitive impairment. However, it is not clear whether cognitive impairment may depend on concomitant psychopathology, since several psychiatric conditions, e.g. schizophrenia, include cognitive deficits among their manifestations.

To assess cognitive performances and psychopathology in obese patients, and to compare cognitive alterations in obese patients with those in schizophrenics and controls.

To compare cognitive performances in obese patients to normal percentiles. To provide an analysis of correlation with specific psychopathological domains. To evaluate whether cognitive performances in very obese patients were different from those in schizophrenia patients and non-affected controls.

88 obese patients were included. Exclusion criteria were: axis I and II diagnosis; severe medical, neurological, or endocrinology conditions. Patients underwent an extensive battery of cognitive tests and completed the Toronto Alexithymia Scale (TAS-20), the Barratt Impulsiveness Scale (BIS-11), the Beck Depression Inventory (BDI), the State-Trait Anxiety Inventory (STAI). In the second part of the study, very obese patients (BMI>40; n=16) were compared for cognitive performances to schizophrenia patients (n=16) and non-affected controls (n=17).

Obese patients performed at low percentiles (<15) on the Problem Solving and the Social Cognition tasks. Mean scores on psychopathology rating scales did not reach abnormal values. No correlation was found with psychopathology. When compared to schizophrenics, no significant differences were found in performances on spatial working memory.

Obese patients show cognitive alterations even in the absence of abnormal psychopathology. Very obese patients share cognitive alterations with schizophrenia patients, which may imply common neurobiological basis.