Objectives:With the rapid growth of the older population worldwide, understanding how older adults with mild cognitive impairment (MCI) use memory strategies to mitigate cognitive decline is important. This study investigates differences between amnestic and nonamnestic MCI subtypes in memory strategy use in daily life, and how factors associated with cognition, general health, and psychological well-being might relate to strategy use.Methods:One hundred forty-eight participants with MCI (mean age = 67.9 years, SD = 8.9) completed comprehensive neuropsychological, medical, and psychological assessments, and the self-report ‘Memory Compensation Questionnaire’. Correlational and linear regression analyses were used to explore relationships between memory strategy use and cognition, general health, and psychological well-being.Results:Memory strategy use does not differ between MCI subtypes (p > .007) despite higher subjective everyday memory complaints in those with amnestic MCI (p = .03). The most marked finding showed that increased reliance-type strategy use was significantly correlated with more subjective memory complaints and poorer verbal learning and memory (p < .01) in individuals with MCI. Moreover, fewer subjective memory complaints and better working memory significantly predicted (p < .05) less reliance strategy use, respectively, accounting for 10.6% and 5.3% of the variance in the model.Conclusions:In general, the type of strategy use in older adults with MCI is related to cognitive functioning. By examining an individual’s profile of cognitive dysfunction, a clinician can provide more personalized clinical recommendations regarding strategy use to individuals with MCI, with the aim of maintaining their day-to-day functioning and self-efficacy in daily life.
Study Objectives Cardiovascular autonomic dysfunction, as measured by short-term diurnal heart rate variability (HRV), has been reported in older adults with mild cognitive impairment (MCI). However, it is unclear whether this impairment also exists during sleep in this group. We therefore compared overnight HRV during sleep in older adults with MCI and those with subjective cognitive impairment (SCI). Methods Older adults (n=210) underwent overnight polysomnography. Eligible participants were characterised as multi-domain MCI or SCI. The multi-domain MCI group was comprised of amnestic and non-amnestic subtypes. Power spectral analysis of HRV was conducted on the overnight electrocardiogram during non-rapid eye movement (NREM), rapid eye movement (REM), N1, N2, N3 sleep stages and wake periods. High-frequency HRV (HF-HRV) was employed as the primary measure to estimate parasympathetic function. Results The MCI group showed reduced HF-HRV during NREM sleep (p=0.018), but not during wake or REM sleep (p>0.05) compared to the SCI group. Participants with aMCI compared to SCI had the most pronounced reduction in HF-HRV across all NREM sleep stages – N1, N2 and N3, but not during wake or REM sleep. The naMCI sub-group did not show any significant differences in HF-HRV during any sleep stage compared to SCI. Conclusions Our study showed that amnestic MCI participants had greater reductions in HF-HRV during NREM sleep, relative to those with SCI, suggesting potential vulnerability to sleep-related parasympathetic dysfunction. HF-HRV especially during NREM sleep may be an early biomarker for dementia detection.
Background Nocturnal high‐frequency heart rate variability (HF‐HRV), an indicator of parasympathetic tone, is decreased in older adults with amnestic mild cognitive impairment (aMCI) during slow wave sleep. However, it is unclear whether or how this parasympathetic dysfunction relates to early cognitive decline. We therefore aimed to explore associations between nocturnal HF‐HRV during slow wave sleep and verbal memory retention in older adults at risk for dementia, and whether this relationship is related to amygdala volume, a sub‐cortical brain region linked to both verbal memory and parasympathetic modulation. Method Older adults attending a memory clinic for cognitive concerns (n=313, mean age 67 years, SD 8.51) completed medical and neuropsychological assessments (including Rey Auditory Verbal Learning Test to assess verbal memory retention). Participants were classified by clinical consensus as aMCI (n=99), non‐amnestic mild cognitive impairment (naMCI; n=134), or subjective cognitive impairment (SCI; n=80). Participants also underwent overnight polysomnography with continuous heart rate recordings. Power spectral analysis of HF‐HRV was analysed for slow wave sleep periods. T1‐weighted magnetic resonance imaging was performed in a sub‐set of participants (n=210) and amygdala (left and right) volumes were derived. All statistical analyses were adjusted for known confounders (age, education). Result A significant association between lower slow wave sleep HF‐HRV and poorer verbal memory retention was evident in aMCI group (r=0.393, p=0.004) only, (SCI: r=‐0.092, p=0.464; naMCI: r=0.038, p=0.759). Multiple regression analysis (R2=0.440; p<0.001) revealed poorer verbal memory retention in the aMCI group was predicted by reduced HF‐HRV (7.5%), older age (6.3%), and lower levels of education (6.8%). While left amygdala volume (3%) did not independently predict verbal memory retention, a significant interaction indicated that those with larger left amygdala volumes and greater HF‐HRV had superior verbal memory retention (HF_HRV*left amygdala; 7.1%). Conclusion Specific to older adults with aMCI, our data showed that parasympathetic modulation during slow wave sleep, particularly for those with larger amygdala volume, may play a key role in memory consolidation. Given that older adults with aMCI are at greater risk of developing dementia due to Alzheimer’s disease, reduced nocturnal parasympathetic activity may be an early marker of cognitive decline in Alzheimer’s disease.
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