Evaluation of the Cognitive Performance of Hypertensive Patients with Silent Cerebrovascular Lesions

Summary

Here, we present a protocol to assess whether various types of silent cerebrovascular lesions are differentially associated with deficits in certain cognitive domains in a cohort of 398 hypertensive elderly Chinese, using a combination of neuropsychological tests and multi-sequence 3T MRI scanning.

Abstract

Evidence accumulated from the last decade has proven that silent cerebrovascular lesions (SCLs) and their underlying pathogenic processes contribute to cognitive decline in the elderly. However, the distinct effects of each type of the lesions on cognitive performance remain unclear. Moreover, research data from Chinese elderly with SCLs is scarce. In this study, 398 otherwise healthy hypertensive elderly subjects (median age 72 years) were included and assessed. All participates were required to complete a battery of structured neuropsychological assessment, including forward and backward digit span tests, symbol digit modalities test, Stroop test, verbal fluency test and Montreal Cognitive Assessment. These tests were used to assess attention, executive function, information processing speed, language, memory and visuospatial function. A multi-sequence 3T MRI scanning was arranged within one month of the neuropsychological assessment to evaluate the burden of SCLs. SCLs were rated visually. Cerebral microbleeds (CMBs) and silent lacunes (SLs) were identified as strictly lobar CMBs and SLs or deep CMBs and SLs according to their locations, respectively. Similarly, white matter hyperintensities (WMHs) were separated into periventricular WMHs (PVHs) and deep WMHs (DWMHs). A series of linear regression models were used to assess the correlation between each type of SCLs and individual cognitive function domain. The results showed that CMBs tend to impair language-related cognition. Deep SLs affect executive function, but this association disappeared after controlling for other types of SCLs. PVHs, rather than DWMHs, are associated with cognitive decline, especially in executive function and processing speed. It is concluded that different aspects of SCLs have differential impact on cognitive performance in hypertensive elderly Chinese.

Introduction

Silent lacunes (SLs), cerebral microbleeds (CMBs) and white matter hyperintensities (WMHs) are referred to as silent cerebrovascular lesions (SCLs). Two types of WMHs are recognized: periventricular WMHs (PVHs) and deep WMHs (DWMHs). SCLs were once regarded as benign lesions without clinical significance. After decades of research, SCLs are now confirmed to be linked to varying functional impairment and cognitive deficits^1,2. Nevertheless, consistent evidence is still limited in the spectrum and magnitude of cognitive effects of different types of SCLs. Moreover, the underlying mechanisms are elusive.

Protocol

The study protocol was approved by the Institutional Review Board of the University of Hong Kong / Hospital Authority Hong Kong West Cluster (HKU/HA HKW IRB) for human research.

1. Participants

1. Recruit otherwise healthy elderly Chinese subjects (from 65 to 99 years old, mean age 72) with a history of hypertension for at least 5 years.
2. Exclude participants with any disease affecting the cognitive function and/or with any disability hindering the completion of the required .......

Discussion

In the study, we have combined the results of a battery of neuropsychological assessment and findings of a multi-sequence MRI examination to evaluate the impact of different types of SCLs on various cognitive functions. The major types of SCLs were examined (i.e., CMBs, SLs and WMHs). As previous studies have revealed that SCLs in different locations may represent different pathology and lead to different consequences, we categorized CMBs and SLs into strictly lobar (i.e., lobar only without deep ones) and deep ones (wit.......

Materials

Name	Company	Catalog Number	Comments
3T MRI	Philips Medical Systems