Cluster analysis and patterns of findings on cranial magnetic resonance imaging of the elderly - The cardiovascular health study

Objective: To characterize patterns of findings on cranial magnetic resonan ce imaging (MRI) of the elderly using a statistical technique called cluste r analysis. Subjects and Methods: The Cardiovascular Health Study is a population-based , longitudinal study of 5888 people 65 years and older. Of these, 3230 unde rwent cranial MRI scans, which were coded for presence of infarcts and grad es for white matter, ventricles, and sulci. Cluster analysis separated part icipants into 5 clusters based solely on patterns of MRI findings. Particip ants comprising each cluster were contrasted with respect to cardiovascular risk factors and clinical manifestations. Results: One cluster was low on all the MRI findings (normal) and another w as high on all of them (complex infarcts). Another cluster had evidence for infarcts alone (simple infarcts), whereas the last 2 clusters lacked infar cts, one having enlarged ventricles and sulci (atrophy) and the other havin g prominent white matter changes and enlarged ventricles (leukoaraiosis). F actors that distinguished these clusters in a discriminant analysis were ag e, sex, several measures of hypertension, internal carotid artery wall thic kness, smoking, and prevalent claudication before the MRI. The atrophy grou p had the highest percentage of men and the normal group had the lowest. Co gnitive and motor performance also differed across clusters, with the atrop hy cluster performing better than may have been expected. Conclusions: These MRI patterns identified participants with different vasc ular disease risk factors and clinical manifestations. Results of these exp loratory analyses warrant consideration in other populations of elderly peo ple. Such patterns may provide clues about the pathophysiology of structura l brain changes in the elderly.