Abstract TMP115: Carotid Atherosclerosis Progression and Hippocampal Volume

Abstract

Background: Carotid atherosclerosis is a known risk factor for stroke and dementia. Carotid atherosclerosis may play a role in neurodegeneration and be a potential target for treatment and preventive efforts for stroke and dementia in asymptomatic individuals. We studied the association of carotid intima media thickness (CIMT) with hippocampal volume (HV) in community-dwelling individuals, and hypothesize that persons with carotid atherosclerosis progression would have a lower HV. Methods: We studied 1,376 Framingham Offspring participants (age 67±8.7 years; 53% women) with two carotid ultrasound measurements (1995-1998 and 2005-2008) and brain MRI scans at or near the second ultrasound, who were stroke, dementia, or other neurological illnesses-free at MRI. We used multivariable linear regression analyses to relate annualized carotid IMT change at internal [ICA] and common carotid [CCA] to HV volume (as a percentage of total cranial volume). Models were adjusted for age, sex, time interval between second carotid duplex and MRI, systolic blood pressure, hypertension treatment (HRx), diabetes, total cholesterol level, smoking, cardiovascular disease and baseline CIMT. We additionally assessed effect modification by HRx and statin use. Results: Mean (±SD) carotid IMT change per year was 0.064±0.082mm in ICA and 0.008±0.008 mm in CCA. Participants with higher ICA IMT progression had significantly lower HV after adjustment for vascular risk factors and baseline IMT (β±SE [standardized beta±standard error]: -0.067±0.027, p= 0.01), but not CCA IMT progression (β±SE: 0.01± 0.0276 p= 0.72). In subgroup analyses, we observed weaker association between ICA IMT change and HV among subjects with HRx (β = -0.047, p=0.19 vs. β =-0.096, p=0.026 in untreated individuals), but HRx by IMT change interaction was not statistically significant (p-interaction=0.39). Effects were similar in statin subgroups and statistically non-significant for CCA IMT progression. Conclusions: Cumulative vascular risk factor exposure, as reflected by ICA IMT progression, are associated with neurodegeneration represented by lower hippocampal volumes. Such changes occur prior to onset of clinical dementia, suggesting that carotid IMT may be a target for preventive efforts.