Defining Vascular Cognitive Impairment in India--A Descriptive Study of MRI Volumetry vs. Cognition in 'Normal' Adults

BackgroundIt is important to establish criteria to define Vascular Cognitive Impairment (VCI) in India as VCI is an image-based diagnosis and MRI changes resulting from age with prevalent vascular risk factors may confound MRI interpretation. ObjectiveTo establish normative community data for MRI volumetry including white matter hyperintensity volume (WMHV), correlated with age-stratified cognitive scores and vascular risk factors in adults [≥]40 years old. Materials and MethodsWe screened 2651 individuals without known neurological morbidity, living in Mumbai and nearby rural areas, using validated Marathi translations of Kolkata Cognitive Battery (KCB) and Geriatric depression score (GDS). We stratified 1961 persons with GDS [≤]9 by age and cognitive score, and randomly selected ten percent from each subgroup for MRI brain volumetry. Crude volumes were standardized to reflect percentage of intracranial volume. ResultsMRI volumetry studies were done in 199 individuals (F/M = 90/109; 73 with BMI [≥]25; 44 hypertensives; 29 diabetics; mean cognitive score 76.5). Both grey and white matter volumes decreased with increasing age. WMHV increased with age and hypertension. Grey matter volume decreased with increasing WMHV. Positive predictors of cognition included standardized hippocampal volume (HCV), urban living, education, and BMI, while WMHV and age were negative predictors. Urban dwellers had higher cognitive scores than rural, and (paradoxically) smaller HCV. ConclusionsFurther study is warranted into sociodemographic and biological factors that mutually influence cognition. Our findings contribute to baseline diagnostic criteria for VCI and could help in early diagnosis and control of cognitive decline and its key risk factors.