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The following is a summary of “Altered functional connectivity and hyperactivity of the caudal hippocampus in schizophrenia compared with bipolar disorder: a resting state fMRI (functional magnetic resonance imaging) study,” published in the February 2025 issue of BMC Psychiatry by Zhang et al. 

Schizophrenia involves hippocampal structural and functional abnormalities linked to specific symptoms. The caudal hippocampus plays a key role in these dysfunctions. 

Researchers conducted a retrospective study to assess functional connectivity (FC) and activity abnormalities in hippocampal subregions in schizophrenia compared to bipolar disorder (BD) and healthy control (HC) groups.  

They examined basal activation state and functional connectivity (FC) in 4 hippocampal subregions: left caudal (cHipp_L), right caudal (cHipp_R), left rostral (rHipp_L), and right rostral (rHipp_R). They analyzed resting-state fMRI from 62 patients with schizophrenia, 57 patients with BD, and 45 patients with HCs, measuring the fractional amplitude of low-frequency fluctuations (fALFF) for basal activity and whole-brain FC. 

The results showed greater fALFF in bilateral cHipp and rHipp in schizophrenia than BD and HC. FC increased between bilateral cHipp and the thalamus, putamen, middle frontal gyrus, parietal cortex, and precuneus. fALFF in bilateral cHipp correlated positively with symptom severity on the Positive and Negative Syndrome Scale. 

Investigators confirmed the role of cHipp dysfunction in schizophrenia. Hyper-connectivity and hyperactivity of the cHipp could serve as a biomarker for therapy development. 

Source: bmcpsychiatry.biomedcentral.com/articles/10.1186/s12888-025-06632-7