Background: Ischemic stroke with cognitive impairment is a considerable risk factor for developing dementia. Identifying imaging markers of cognitive impairment following ischemic stroke will help to develop prevention strategies against post-stroke dementia.
Methods: We investigated the hippocampal functional connectivity (FC) pattern following ischemic stroke, using resting-state fMRI (rs-fMRI). Thirty-three cognitively impaired patients after ischemic stroke and sixteen age-matched controls with no known history of neurological disorder were recruited for the study. No patient had a direct ischaemic insult to hippocampus on the examination of brain imaging. Seven subfields of hippocampus were used as seeds region for FC analyses.
Results: Across all hippocampal subfields, FC with the inferior parietal lobule was reduced in stroke patients as compared with healthy controls. This decreased FC included both supramarginal gyrus and angular gyrus. The FC of hippocampal subfields with cerebellum was increased. Importantly, the degree of the altered FC between hippocampal subfields and inferior parietal lobule was associated with their impaired memory function.
Conclusion: Our results demonstrated that decreased hippocampal-inferior parietal lobule connectivity was associated with cognitive impairment in patients with ischemic stroke. These findings provide novel insights into the role of hippocampus in cognitive impairment following ischemic stroke.
Bibliographical noteFunding Information:
AAH was the Principal Investigator of the Hippocampal Pathology in Post-Stroke Cognitive Impairment (HiPPSCI) Study (Co-Investigators: PR, DPA, MW, Don Sims, Sissi Ispoglou, Vijay Sawlani, and Tom Hayton). The study received funding from the Stroke Association, UK (TSA PGF 2016–02) awarded to RL for her PhD that was supervised by PR and AAH. HiPPSCI was co-funded by the Midland Neurosciences Teaching and Research Fund. AAH is currently funded by the Medical Research Council, UK (grant MR/T005580/1)
We would like to acknowledge study co-investigators not listed as co-authors, the research nurses at Sandwell General Hospital and Queen Elizabeth Hospital Birmingham, and the Birmingham University Imaging Centre (now the Centre for Human Brain Health) for supporting the study. Additionally, Rachel Evans and students; Emily Todd and Alicia Northall for the support in data collection.
- Cognitive impairment
- Functional connectivity
- Ischemic stroke
- Resting-state functional magnetic resonance imaging
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging
- Clinical Neurology
- Cognitive Neuroscience