Even Emil Kraepelin's description of dementia praecox emphasized the change in cognition and the long-term deteriorating course of schizophrenic patients, opposed to the ones having manic-depressive psychosis or paranoia.

Currently, neurocognitive impairment is considered a core component of schizophrenia, particularly affecting the domains of attention, executive-frontal lobe function, working memory, and episodic memory. The dorsolateral prefrontal cortex has been implicated in cognitive disorganization and current therapeutic options have only a modest effect on this chronic disability. Although these impairments cannot function as diagnostic tools, they are strongly related to the functional outcome of the illness, and have significant prognostic value.

Negative symptoms, such as poverty of speech or blunted affect, are among the most chronic symptoms of schizophrenia. They respond poorly to antipsychotics, and are widely suspected to reflect a dorsolateral frontal lobe dysfunction, as well. This negative dimension is associated with a poor long-term cognitive outcome and may be closely related to the primary cognitive deficit in schizophrenia.

Objectives and methods: The authors aim to provide an overview of the existing literature regarding these dimensions of schizophrenia, and the hypotheses of a possible association between schizophrenia and dementia.

Given the prognostic value of mild cognitive impairment, and regardless of the evidence of frontal lobe dysfunction in schizophrenia, few studies have examined the longitudinal relationship between psychosis and the development of (frontotemporal) dementia. This theoretical association raises the possibility that these distinct entities could result from a common neurodegenerative pathway.