Association between sleep health and cognitive reserve in older adults with cognitive concerns

Abstract

AbstractBackgroundWe examined the association between sleep health consequences and perceived fatigability within the context of carrying out everyday activities in non‐demented older adults and investigated whether cognitive reserve (CR; individual differences in susceptibility to cognitive decline due to brain aging, pathology, or insult) moderated this relationship.MethodThis was a cross‐sectional study. We prospectively screened adults age 55‐90 years at a Memory Research Clinic. An IRB approved the study protocol, and informed consent was obtained. Patients with cognitive concerns underwent neurocognitive testing to determine cognitive status based on the ADNI criteria. Inclusion criteria: the ADNI criteria for cognitively normal or MCI. Exclusion criteria: 1) depression assessed with the Geriatric Depression Scale (GDS>5) and DSM‐5 criteria, 2) history of primary psychiatric illnesses, 3) medical conditions associated with fatigue, and 4) a history of obstructive sleep apnea diagnosed by a clinical sleep physician. Measures included the PROMIS Sleep‐related Impairment (SRI); the Neuro‐QOL Cognitive function (CogF) and Fatigue measure, which yields “fatigue symptom severity (Fat_Sx)” and “perceived fatigability (Fatiga)” subscales. CR was assessed with the CR Index questionnaire (CRIq). Linear regression models were fit to the fatigue outcomes and included the SRI, CR, and their interaction as predictors. If the interaction was significant, SRI slopes were assessed at CR=mean and mean ±1SD. All analyses were adjusted for age, sex, and education.ResultThere were 37 subjects in this study; mean age of 70.8 years (SD=9.3); 70.3% subjects were female; 86.5% white, 10.8% Hispanic, and 2.7% others. CR significantly moderated the relationship between SRI and perceived fatigability (F (1,32)=18.64, p=0.011). A higher SRI score was associated with a higher perceived fatigability severity with a low CR (CRIq mean‐1SD)=108.6; b(se)=.493(.089), p<0.001) and a mean CR (CRIq mean=128.0; b(se)=.274(.076); p=0.001), but not a high CR (CRIg mean+1SD=147.4; b(se)=0.1278; p=0.636). Moreover, higher perceived fatigability was associated with lower cognitive function (b(se)=‐.24 2(0.077), p=0.004), controlling for age, gender, and education.ConclusionPoorer cognitive function was significantly associated with greater fatigability within the context of managing everyday activities. Greater cognitive reserve may reduce the detrimental influence of poor sleep health on perceived fatigability in managing daily function during the preclinical stages of dementia.