Processing speed in normal aging: effects of white matter hyperintensities and hippocampal volume loss

Changes in cognitive functioning are said to be part of normal aging. Quantitative MRI has made it possible to measure structural brain changes during aging which may underlie these decrements which include slowed information processing and memory loss. Much has been written on white matter hyperintensities (WMH), which are associated with cognitive deficits on tasks requiring processing speed and executive functioning, and hippocampal volume loss, which is associated with memory decline. Here we examine volumetric MRI measures of WMH and hippocampal volume loss together in relation to neuropsychological tests considered to be measures of executive functioning and processing speed in 81 non-demented elderly individuals, aged 75-90. Correlational analysis showed that when controlling for age, both greater WMH volume and smaller hippocampal volume were correlated with slower performances on most tests with the exception of a battery of continuous performance tests in which only WMH was correlated with slower reaction time (RT). We then performed a series of hierarchical multiple regression analyses to examine the independent contributions of greater WMH volume and reduced hippocampal volume to executive functioning and processing speed. The results showed that for the four measures requiring executive functioning and speed of processing, WMH volume and hippocampal volume combined predicted between 21.4% and 37% of the explained variance. These results suggest that WM integrity and hippocampal volume influence cognitive decline independently on tasks involving processing speed and executive function independent of age.

Caregiver burden and depression in mild cognitive impairment

Little is known about contributors to burden and depression in caregivers of patients with mild cognitive impairment (MCI) even though these patients experience cognitive, emotional, and behavioral changes. We examined caregiver burden and depression in 43 caregivers for patients with MCI as well as their associations with patients' neuropsychological status and behavioral symptoms. Almost 30% of caregivers reported clinically significant burden, whereas <5% reported significant depression. Increased caregiver burden was associated with greater disinhibited behaviors by patients, whereas increased caregiver depressive symptoms were associated with greater disinhibited behaviors as well as instrumental activity of daily living (ADL) impairments. Caregiver burden and depression were not associated with patients' neuropsychological performance. Results suggest these caregivers would benefit from interventions addressing both practical methods to provide ADL assistance and behavioral methods to address inappropriate behaviors in patients in the predementia stages.

Use of the telephone-administered Minnesota Cognitive Acuity Screen to detect mild cognitive impairment

This study determined the sensitivity and specificity of the telephone-administered Minnesota Cognitive Acuity Screen (MCAS) to distinguish mild cognitive impairment (MCI) from healthy controls (HCs) and from Alzheimer's disease (AD). A total of 100 individuals with MCI, 50 individuals with possible/probable AD, and 50 HCs were screened to exclude medical and psychiatric conditions affecting cognition. In-office evaluation included neuropsychological testing, neurologic examination, and neurodiagnostic work-up. Participants with AD obtained significantly lower MCAS total scores than participants with MCI, who in turn performed worse than the HC group. Sensitivity was 86% and specificity was 78% for distinguishing between MCI and HC. Sensitivity was 86% and specificity was 77% for discriminating between MCI and AD. Sensitivity was 91% and specificity was 78% for discriminating between impaired groups (MCI and AD) and HCs. Results suggest that the MCAS successfully discriminates MCI from HC and AD and has potential as an effective telephone-administered screening tool for memory disorders.