Quantitative MRI findings and cognitive impairment among community dwelling elderly subjects

Abstract

Objectives: To study the factors which influence cognitive impairment among elderly subjects living in a local community, based on both MRI and clinical findings, to further elucidate the causes of dementia, and also to help develop strategies for its prevention. Methods: Cranial MRI and other medical examinations were performed on non-demented elderly subjects who resided in one rural community. A total of 254 subjects aged from 60 to 91 years of age, with a mean age of 73.9 (SD 6.8) were examined. The mini mental state examination (MMSE) was used to identify cognitive impairment. White matter lesions and cerebral atrophy on MR images were measured quantitatively. A multivariate analysis was also performed with the existence of cognitive impairment as the dependent variable, and the MRI findings and clinical observations were used as the independent variables. Results: Cognitive impairment was present in 46 subjects (18.1%). They were older, had a lower educational level, and more frequent hypertension compared with those without cognitive impairment. The packed cell volume was lower in the impaired group. In addition, their MRI findings showed significantly larger quantities of white matter lesions and cerebral atrophy, as well as more infarcts. A logistic regression analysis demonstrated a significant relation among such factors as white matter lesions (odds ratio (OR) 1.575, 95% confidence interval (95% CI) 1.123-2.208), cerebral atrophy (OR 0.761, 95%CI 0.587-0.987), and lower education (OR 0.682, 95%CI 0.544-0.855) for subjects with a cognitive impairment. Conclusions: White matter lesions and cerebral atrophy are factors which induce a cognitive impairment in community dwelling elderly subjects without dementia. It is important to carefully watch for any abnormalities in these factors, and to perform cohort studies to check for the above risk factors, to both prevent and make an early diagnosis of dementia. E lucidating the causes of dementia as well as making an early diagnosis, and developing strategies to prevent dementia are matters of extreme urgency in our aging society. So far several reports have been published on large scale examinations of the general population to investigate the course of dementia before and after its onset. [1][2][3][4][5][6] There are also many reports about the influence of certain specific risk factors, such as white matter lesions, silent cerebral infarction, and other risk factors related to cognitive function. However, there have been few comprehensive studies which focus on cognitive impairment and the factors which influence them, based on both clinical observation and image examinations. In the present study, we performed cranial MRI and other procedures in elderly subjects who lead a normal life at home and investigated the factors influencing cognitive function based on a multivariate analysis. In particular, abnormal findings on MRI such as white matter lesions and cerebral atrophy were measured quantitatively. We herein report our findings which led to the conclu...

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