Mesiotemporal atrophy and hippocampal diffusivity distinguish amnestic from non-amnestic vascular cognitive impairment

Abstract

Background and purpose: The role of clinical factors, cerebral infarcts and hippocampal damage in vascular cognitive impairment (VCI) subtypes remains unclear. Methods: Non-demented patients with carotid stenosis and recent transient ischemic attack/stroke had cognitive assessment and brain magnetic resonance imaging (MRI). Amnestic VCI was defined as memory impairment; non-amnestic VCI was any other subdomain impairment. Associations of MRI metrics [log-transformed total ischemic lesion load (log TILL), mesiotemporal atrophy (MTA) score, hippocampal mean diffusivity (hipMD)] with cognitive performance were assessed. Results: A hundred and eight patients, 47 with amnestic VCI and 21 with non-amnestic VCI, were assessed. A higher MTA (odds ratio 12.89, P = 0.001) and left hipMD (odds ratio 4.43, P = 0.003) contributed to amnestic VCI versus normal. Age-adjusted fluency correlated with log TILL (P = 0.002). Age-adjusted memory was associated with left hipMD (P = 0.001), MTA (P < 0.001) but not log TILL (P = 0.14). Left hipMD, MTA and smoking showed classification potential between amnestic VCI versus normal (area 0.859, P < 0.001). Conclusions: Neuroimaging assists stratification in amnestic VCI characterized by hippocampal changes and in non-amnestic VCI by higher ischemic burden. MTA and hippocampal diffusivity show diagnostic biomarker potential.