Structural connectivity between the hippocampus and cortical/subcortical area relates to cognitive impairment in schizophrenia but not in mood disorders

Abstract

Cognitive impairment in schizophrenia and other psychiatric disorders is a challenge to be overcome in order to maintain patients' quality of life and social function. The neurological pathogenesis of cognitive impairment requires further elucidation. In general, the hippocampus interacts between the cortical and subcortical areas for information processing and consolidation and has an important role in memory. We examined the relationship between structural connectivity of the hippocampus and cortical/subcortical areas and cognitive impairment in schizophrenia, major depressive disorder and bipolar disorder. Subjects comprised 21 healthy controls, 19 patients with schizophrenia, 20 patients with bipolar disorder and 18 patients with major depressive disorder. Diffusion-weighted tensor images data were processed using ProbtrackX2 to calculate the structural connectivity between the hippocampus and cortical/ subcortical areas. Cognitive function was assessed using the Brief Assessment of Cognition in schizophrenia composite score. Hippocampal structural connectivity index was significantly correlated with composite score in the schizophrenia

Impaired large-scale cortico–hippocampal network connectivity, including the anterior temporal and posterior medial systems, and its associations with cognition in patients with first-episode schizophrenia

“…At the within-network level, we discovered decreased intrinsic FC in the cortico-hippocampal network, including the AT system, the PM system, and the anterior and posterior hippocampus, which is partially consistent with prior reports for schizophrenia (Benetti et al, 2009;Belujon et al, 2013;Liu et al, 2020;Wang et al, 2021;Ikeda et al, 2022;Walther et al, 2022). The corticohippocampal network plays a critical role in cognition, especially memory: AT is mainly involved in recognition and associative memory, affective processing, semantic processing, and object perception (Diana et al, 2007), while PM is implicated in episodic and autobiographical memory for the context of an event, space and time, scene perception, and social cognition (Johnson and Rugg, 2007).…”

Volumes of hippocampal subfields suggest a continuum between schizophrenia, major depressive disorder and bipolar disorder

“…The parasubiculum is also associated with the integration of information procession between hippocampus and cortex. The structural connections between the hippocampus and cortical/subcortical areas relates to cognitive impairment have been found in SZ but not in MDD (74,75). Two recent studies reported a volume reduction in parasubiculum in patients with MDD compared to HC, which correlated with plasma BDNF levels (76,77).…”