Slower gait speed increases risk of falling in older adults with depression and cognitive complaints.

Slowed gait is one of the strongest predictors of fall risk in older adults. The present study investigated whether gait speed mediated the relationship between depression and fall history in 147 older adults presenting to a memory clinic for cognitive complaints. Depression, cognitive status, gait speed, and number of falls within the last year were the primary measures. Results revealed fallers, relative to non-fallers, had slower gait speed and higher depression scores. As hypothesized, analyses using the PROCESS macro found that gait mediated the relationship between depression and fall history. Additionally, the combination of depression and mild cognitive impairments (MCI) associated with a significantly greater likelihood of falling. Our findings indicate that combined depression and MCI have additive effects on fall risk, likely through the destabilizing effect of slowed gait on balance. Better understanding the underlying pathophysiology involved in MCI and depression-related gait disturbances may lead to improved intervention targets for fall risk prevention.

Brain Reserve in a Case of Cognitive Resilience to Severe Leukoaraiosis.

OBJECTIVE: Leukoaraiosis, or white matter rarefaction, is a common imaging finding in aging and is presumed to reflect vascular disease. When severe in presentation, potential congenital or acquired etiologies are investigated, prompting referral for neuropsychological evaluation in addition to neuroimaging. T2-weighted imaging is the most common magnetic resonance imaging (MRI) approach to identifying white matter disease. However, more advanced diffusion MRI techniques may provide additional insight into mechanisms that influence the abnormal T2 signal, especially when clinical presentations are discrepant with imaging findings. METHOD: We present a case of a 74-year-old woman with severe leukoaraoisis. She was examined by a neurologist, neuropsychologist, and rheumatologist, and completed conventional (T1, T2-FLAIR) MRI, diffusion tensor imaging (DTI), and advanced single-shell, high b-value diffusion MRI (i.e., fiber ball imaging [FBI]). RESULTS: The patient was found to have few neurological signs, no significant cognitive impairment, a negative workup for leukoencephalopathy, and a positive antibody for Sjogren's disease for which her degree of leukoaraiosis would be highly atypical. Tractography results indicate intact axonal architecture that was better resolved using FBI rather than DTI. CONCLUSIONS: This case illustrates exceptional cognitive resilience in the face of severe leukoaraiosis and the potential for advanced diffusion MRI to identify brain reserve.

Dual-Task Gait Assessment in a Clinical Sample: Implications for Improved Detection of Mild Cognitive Impairment.

OBJECTIVES: Research has longitudinally linked dual-task gait dysfunction to mild cognitive impairment (MCI) and dementia risk. Our group previously demonstrated that dual-task gait speed assessment distinguished between subjective cognitive complaints (SCC) and MCI in a memory clinic setting, and also found that differences in dual-task gait speed were largely attributable to executive attention processes. This study aimed to reproduce these findings in a larger diverse sample and to extend them by examining whether there were group differences in single- versus dual-task cognitive performance (number of letters correctly sequenced backward). METHOD: Two-hundred fifty-two patients (M age = 66.01 years, SD = 10.46; 119 MCI, 133 SCC) presenting with cognitive complaints in an academic medical setting underwent comprehensive neuropsychological and gait assessment (single- and dual-task conditions). RESULTS: Patients with MCI walked slower and showed greater decrement in cognitive performance than those with SCC during dual-task conditions. Neuropsychological measures of executive attention accounted for significant variance in dual-task gait performance across diagnostic groups beyond demographic and health risk factors. DISCUSSION: Reproduction of our results within a sample over four times the previous size provides support for the use of dual-task gait assessment as a marker of MCI risk in clinical settings.

Posterior cortical atrophy of a suspected non-Alzheimer type: a case report.

OBJECTIVE: A case of Posterior Cortical Atrophy syndrome of a suspected non-Alzheimer disease pathology type is presented to illustrate prospective diagnosis and course. METHOD: A 54-year-old woman with vague memory complaints underwent serial neuropsychological assessment, MRI, PET, and CSF screening; data are reviewed. RESULTS: While early diagnosis was confounded by multiple factors, classic visuospatial symptoms were later demonstrated using routine neuropsychological methods. Serial MRI, PET, and CSF screening argued strongly for an alternative underlying pathology to AD. At age 59, her condition had progressed to dementia. CONCLUSIONS: Findings underscore the need for further research on suspected non-amyloid-based pathologies.