Episodic retrieval is characterized by the subjective experience of remembering. Semantic memory, on the other hand, is a more structured record of facts, meanings, concepts and knowledge about the external world that we have acquired. The medial temporal lobe (MTL), especially the hippocampus and parahippocampal cortex, plays a central role in both types of memory process. Published studies suggested that individuals with schizophrenia have deficits in episodic and semantic memory, as well as structural abnormalities of the medial temporal lobe. However, it is not clear whether reported correlations reflect the impact of the disease state or that of underlying genetic influences contributing to the risk. To understand better etiology and effects of psychosis on the global brain structure and cognitive processing, relatives of individuals with schizophrenia can be studied. The aim of our study was to examine the association between abnormalities of the MTL, psychopathology, and memory impairment in schizophrenia. Study sample (n=60) consisted of first episode schizophrenia patients, their non-psychotic siblings and matching control subjects. We used high-resolution magnetic resonance imaging and probabilistic algorithms for image analysis. Episodic and semantic memory was measured with neuropsychological tests. Our results showed differences in memory performance between the groups. Neuropsychological data were correlated with MRI findings. The results may provide insight into etiology of schizophrenia and its effects on cognition and help to identify neuroanatomical and cognitive endophenotypes of psychotic disorders.

Supported by the grant projects MH CR AZV 15-28998A, MEYS NPU4NUDZ: LO1611; Czech Science Foundation, grant No. 16-13093S; Institutional Support 00023001IKEM.