Declarative memory deficits and schizophrenia: Problems and prospects

Cognitive deficits are among the most important factors leading to poor functional outcomes in schizophrenia, with deficits in declarative memory among the largest and most robust of these. Thus far, attempts to enhance cognition in schizophrenia have shown only modest success, which underlies increasing efforts to develop effective treatment strategies. This review is divided into three main parts. The first section delineates the nature and extent of the deficits in both patients with schizophrenia and in their adult, non-psychotic relatives. The second part focuses on structural and functional abnormalities in the hippocampus, both in people with schizophrenia and in animal studies that model relevant features of the illness. The third section views problems in declarative memory and hippocampal function from the perspective of elevated rates of common medical disorders in schizophrenia, with a focus on insulin insensitivity/diabetes. The likelihood that poor glucose regulation/availability contribute to declarative memory deficits and hippocampal abnormalities is considered, along with the possibility that schizophrenia and poor glucose regulation share common etiologic elements, and with clinical implications of this perspective for enhancing declarative memory.

► Impaired declarative memory performance is a robust finding in schizophrenia research.
► We review these deficits in people with schizophrenia and in non-psychotic relatives.
► Related hippocampal abnormalities are reviewed in people and in animal models.
► Mnemonic and hippocampal dysfunction are viewed in relation to medical problems.
► Implications for enhancing memory in schizophrenia are then considered.