REM sleep latency linked to Alzheimer’s disease, dementia pathophysiology
Key takeaways:
- Prolonged REM sleep latency was associated with three key Alzheimer’s-specific pathological changes.
- REM sleep latency may be a marker for AD and related dementias.
Prolonged rapid eye movement sleep latency may be an early indicator of Alzheimer’s disease and related dementias, according to research conducted in China and published in Alzheimer’s & Dementia.
“Most research on sleep and AD has focused on deep sleep, or slow-wave sleep, but little is known about REM sleep, which is when dreams usually happen,” Yue Leng, PhD, associate professor of psychiatry at Weill Institute for Neurosciences at University of California, San Francisco, told Healio in an email.
As the relationship between rapid eye movement (REM) sleep and biomarkers indicative of AD remains unclear, Leng and colleagues sought to examine this association in a cohort of older adults.
They recruited 128 Chinese adults aged 50 years and older (mean age, 70.8 ± 9.6 years; 56.9% women) from the outpatient neurology unit of the China-Japan Friendship Hospital between September 2022 and July 2023.
Participants underwent overnight polysomnography and amyloid-beta positron emission tomography, as well as analysis of three AD-specific plasma biomarkers: phosphorylated tau at threonine 181 (p-tau181), neurofilament light and brain-derived neurotrophic factor via the Quanterix Simoa platform. In addition, the researchers performed apolipoprotein E4 (APOE4) genotyping via polymerase chain reaction.
Parameters for sleep analysis included total sleep time, sleep efficiency, sleep onset latency, REM sleep latency and percentage of time spent in each of the three phases of REM sleep.
Enrollees also underwent a comprehensive cognitive battery, which included the Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment, Symbol Digit Modalities Test, Digit Span Test and Verbal Fluency Test, in addition to lab tests and infectious disease screening.
Cognitive test analysis revealed that 64 participants had AD, 41 had mild cognitive impairment (MCI) and 23 had normal cognition.
According to the results, participants with AD or MCI had longer REM sleep latency and sleep onset latency compared with individuals with normal cognition, although the differences did not reach statistical significance.
Data further showed individuals diagnosed with AD had lower MMSE scores and a higher proportion were APOE4 carriers; the researchers noted no other statistically significant differences in clinical characteristics across the diagnosis groups.
After adjusting for demographics, APOE status and cognition, the researchers reported that patients in the highest tertile of REM latency had a higher amyloid-beta burden (B = 0.08; 95% CI, 0.03-0.13), elevated p-tau181 (B = 0.19; 95% CI, 0.02-0.13) and lower brain-derived neurotrophic factor levels (B = –0.47; 95% CI, –0.68 to –0.13) compared with patients in the lowest tertile.
“It is important for patients to pay attention to the different aspects of their sleep, not only ‘deep sleep,’” Leng told Healio.