Premium
Left amygdala volume moderates the relationship between nocturnal high‐frequency heart rate variability and verbal memory retention in older adults with amnestic mild cognitive impairment
Author(s) -
Kong Shawn Dexiao,
Hoyos Camilla M,
Phillips Craig L,
McKin Andrew C,
Palmer Jake R,
Duffy Shantel L,
Mowszowski Loren,
Lin Pinghsiu,
Gordon Christopher J,
Naismith Sharon L
Publication year - 2020
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1002/alz.044608
Subject(s) - audiology , verbal memory , heart rate variability , psychology , effects of sleep deprivation on cognitive performance , cognition , polysomnography , amygdala , neuropsychology , medicine , confounding , cardiology , heart rate , psychiatry , electroencephalography , blood pressure
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 (R 2 =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.