Brain Inflammation May Link Alzheimer Disease With Sleep Disturbance

Study shows promising results for early detection and prevention efforts.

A study found that brain inflammation may create a link between sleep disturbance and Alzheimer disease, which may help with prevention and early detection efforts.

The multisite research study aimed to explore the potential effects of inflammation on fast sleep spindles, which research shows promote long-term memory retention. Although sleep disturbance, brain inflammation, and disrupted brain waves have been associated with Alzheimer disease in prior research, this study is the first to investigate the specific interactions.1

The study included 58 participants in their 50s and 60s (mean ± SD; 61.4 ± 6.3 years; 38 females and 20 males) who had a parental history of or genetic risk factor for Alzheimer disease, but were not experiencing cognitive impairment and had no β-amyloid plaques or neurofibrillary tau tangles. The researchers recorded participants’ sleep with high-density electroencephalography to map participants’ brain wave expression during sleep and assess their overnight memory retention. The researchers also examined cerebrospinal fluid biomarkers of β-amyloid and tau proteins, neuronal integrity, and central nervous system inflammation through lumbar puncture.

The researchers found that the activation of microglia and astrocytes—2 types of glial cells that trigger brain inflammation—was associated with the disrupted expression of fast sleep spindles. As the researchers identified these relationships in individuals who had no accumulation of β-amyloid plaques or neurofibrillary tangles, the researchers concluded that inflammation and sleep deficits may be early warning signs of Alzheimer disease.1,2

“Our findings indicate that age-related increases in brain inflammation have a downstream effect on Alzheimer’s disease-related tau proteins and neuronal synaptic integrity. This results in deficits in the brain’s capacity to generate fast sleep spindles, which contribute to age-related memory impairment in older adults,” said Bryce Mander, PhD, assistant professor of psychiatry and human behavior at the University of California, Irvine, and lead and co-corresponding author on the study.

“We don’t know yet whether anyone in this study will develop Alzheimer’s disease dementia, but one of the reasons that our studies enroll participants in midlife is so that we can potentially detect problems before people develop disease symptoms,” added Barbara Bendlin, PhD, professor of medicine at the University of Wisconsin-Madison and co-author on the study. The authors concluded that detecting signs of Alzheimer disease early may help stop cognitive decline associated with age and the disease.1 “Discovering these mechanisms is an important step in identifying at-risk individuals as early as possible and developing targeted interventions,” Mander said.

References

1. Research reveals how brain inflammation may link Alzheimer’s risk, sleep disturbance. University of California, Irvine. News release. July 13, 2022. Accessed July 19, 2022. https://news.uci.edu/2022/07/13/research-reveals-how-brain-inflammation-may-link-alzheimers-risk-sleep-disturbance/

2. Mander BA, Dave A, Liu KK, et al. Inflammation, tau pathology, and synaptic integrity associated with sleep spindles and memory prior to β-amyloid positivity. Sleep. Published online June 7, 2022. Accessed July 19, 2022. https://academic.oup.com/sleep/advance-article-abstract/doi/10.1093/sleep/zsac135/6603598?redirectedFrom=fulltext&login=false