Association between cerebral metabolic and structural abnormalities and cognitive performance in schizophrenia

The possible association in schizophrenia between frontal abnormalities, such as hypofrontality and frontal grey matter (GM) deficits, and neuropsychological deficits is not yet well defined. Our objective was to study such an association and to clarify the cognitive relevance of metabolic and anatomical variability across schizophrenia patients. To do so, we studied dorsolateral prefrontal (DLPF) metabolism during an attention test using fluoro-deoxy-glucose positron emission tomography and DLPF structure with magnetic resonance imaging (MRI) in 22 schizophrenia patients [9 neuroleptic-naive (NN) first episodes]. These patients also underwent a comprehensive battery of neuropsychological tests aimed at evaluating global intelligence and the proposed domains of cognitive alteration in schizophrenia, i.e., attention, visual and verbal learning and memory, working memory, problem solving and processing speed. The metabolic activity in the right DLPF region was significantly and directly related to processing speed, and a measure of structural deficit in the same area was directly related to working memory scores. In the NN group studied alone, these associations were replicated. We may conclude that hypofrontality during cognitive activation, and the degree of DLPF structural deficit may be associated to a particular profile of cognitive deficit, including lower processing speed and working memory capacity.