Strengths and Weaknesses of the Vascular Apathy Hypothesis: A Narrative Review

The Spectrum of Cerebral Small Vessel Disease: Emerging Pathophysiologic Constructs and Management Strategies

Cerebral small vessel disease (CSVD) is a spectrum of disorders that affect small arterioles, venules, cortical and leptomeningeal vessels, perivascular spaces, and the integrity of neurovascular unit, blood brain barrier, and surrounding glia and neurons. CSVD is an important cause of lacunar ischemic stroke and sporadic hemorrhagic stroke, as well as dementia-which will constitute some of the most substantive population and public health challenges over the next century. This article provides an overview of updated pathophysiologic frameworks of CSVD; discusses common and underappreciated clinical and neuroimaging manifestations of CSVD; and reviews emerging genetic risk factors linked to sporadic CSVD.

Racial/ethnic differences in neuropsychiatric disturbances associated with incident dementia

INTRODUCTION

Neuropsychiatric symptoms (NPS) are nearly universal in dementia; some cross-sectional studies of NPS in dementia have found racial/ethnic differences, though it is unknown if NPS prevalence differs among racial/ethnic groups before and after dementia diagnosis.

METHODS

Participants were followed annually at Alzheimer's Disease Centers and were assessed on the Neuropsychiatric Inventory-Questionnaire (NPI-Q) with at least one follow-up visit at which they were diagnosed with dementia. Descriptive statistics were generated by race/ethnicity. NPS were modeled over time as a function of race/ethnicity and with diagnosis date as the baseline.

RESULTS

NPS were present in 95% in at least one time point. After adjusting for covariates, there were no statistically significant differences in NPI-Q total scores among racial/ethnic groups at the time of and after dementia diagnosis.

DISCUSSION

Findings from our prospective cohort study suggest that when individuals are matched at the time of conversion to dementia, there are no racial/ethnic differences in NPS.

Highlights

Neuropsychiatric symptoms of dementia are frequent and increase caregiver burden.Prior studies reported more neuropsychiatric symptoms (NPS) in Black compared to White individuals with dementia.National Alzheimer's Coordinating Center Black, White, and Hispanic participants did not differ in NPS at the time of dementia diagnosis.

Lower cerebrovascular reactivity in prefrontal cortex and weaker negative functional connectivity between prefrontal cortex and insula contribute to white matter hyperintensity-related anxiety or depression

BACKGROUND

White matter hyperintensities (WMHs) are associated with higher anxiety or depression (A/D) incidence. We investigated associations of WMHs with A/D, cerebrovascular reactivity (CVR), and functional connectivity (FC) to identify potential pathomechanisms.

METHODS

Participants with WMH (n = 239) and normal controls (NCs, n = 327) were assessed for A/D using the Hamilton Anxiety Rating Scale (HAMA) and Hamilton Depression Rating Scale (HAMD). The CVR and FC maps were constructed from resting-state functional MRI. Two-way analysis of covariance with fixed factors A/D and WMH was performed to identify regional CVR abnormalities. Seed-based FC analyses were then conducted on regions with WMH × A/D interaction effects on CVR. Logistic regression models were constructed to examine the utility of these measurements for identifying WMH-related A/D.

RESULTS

Participants with WMH related A/D exhibited significantly greater CVR in left insula and lower CVR in right superior frontal gyrus (SFG.R), and HAMA scores were negatively correlated with CVR in SFG.R (r = -0.156, P = 0.016). Insula-SFG.R negative FC was significantly weaker in WMH patients with suspected or definite A/D. A model including CVR plus FC changes identified WMH-associated A/D with highest sensitivity and specificity. In contrast, NCs with A/D exhibited greater CVR in prefrontal cortex and stronger FC within the default mode network (DMN) and between the DMN and executive control network.

LIMITATIONS

This cross-sectional study requires validation by longitudinal and laboratory studies.

CONCLUSIONS

Impaired CVR in SFG.R and weaker negative FC between prefrontal cortex and insula may contribute to WMH-related A/D, providing potential diagnostic imaging markers and therapeutic targets.

Apathy as a determinant of health behaviors in older adults: Implications for dementia risk reduction

INTRODUCTION

Long-term improvements in physical inactivity and other behavioral risk factors are integral to dementia risk reduction; however, sustained behavior change is challenging. Apathy, depression, and fatigue may impact engagement in health behaviors, but their presentation overlaps. This study investigates whether these symptoms are differentially associated with multiple health behaviors.

METHODS

In 1037 community-dwelling older adults without dementia (aged 70-90, 55% women), regression analyses examined apathy, depression, and fatigue as predictors of health behaviors (physical activity, diet, alcohol, smoking) and a behavioral risk index.

RESULTS

Apathy was associated with reduced physical activity and alcohol use, and one or multiple behavioral risk factors. No or inconsistent relations were found between depression or fatigue and health behaviors.

DISCUSSION

Apathy is relevant to multiple health behaviors and should be considered when designing health promotion for older adults, including interventions for dementia risk reduction. Findings highlight the importance of distinguishing apathy from comorbid symptoms.

Highlights

Novel theory-based perspective on behavioural risk factors for dementia.Higher apathy predicted less physical activity and alcohol use, and increased odds of lifestyle risk factors.Depressive symptoms were not associated with any health behavior.Apathy may be a determinant of multiple health behaviors in older adults, distinct from depression and fatigue.Considering apathy in precision prevention of dementia appears warranted.