Arguments against the cognitive dysmetria hypothesis of schizophrenia.

Recently, the 'cognitive dysmetria' theory for schizophrenia has been formulated. According to this theory, a primary neurocognitive dysfunction is the core of schizophrenia and underlies symptom formation. The suggested perceptual fragmentation of external stimuli and inability to connect such perceptions with internal schemata is suggested to lead to positive symptoms, while defensive self-restriction and the exhaustion of the mental apparatus lead to negative symptomatology. Objections to this theory include observations (i) that patients with dominant positive symptoms, e.g., delusions, hallucinations, manifest better neurocognitive function and (ii) that typically antipsychotics significantly reduce positive symptoms and thus improve both the clinical picture and the functioning (to the extent it is reduced with positive symptoms) of the patients, yet have little or no effect on negative, e.g., loss of volition, emotional blunting, and neurocognitive symptomatology, e.g., attentional and memory deficit. The literature suggests that neurocognitive symptoms group independently of other symptomatology. It is suggested that there is currently more evidence against than in favor of the 'cognitive dysmetria' theory.