SEOUL (The Korea Herald/ANN): Abnormal behaviour during rapid eye movement, or REM, sleep may signal deteriorating cognitive ability, a local study showed on Jan 26.
Researchers at Seoul National University Bundang Hospital looked at patients with long-term isolated REM sleep behavior disorder (iRBD), a condition in which people act out their dreams while sleeping, often involving screaming, laughing, and other violent outbursts – the isolated referring to the absence of associated neurological diseases.
They found patients tended to show marked loss of cognitive functions, potentially leading to neurodegenerative diseases such as dementia or Parkinson’s disease.
The cognitive impairment that is commonly observed in iRBD is considered a potential marker of neurodegenerative disorders such as Parkinson’s disease and dementia with Lewy bodies, the researchers wrote.
The team’s goal was to provide long-term data tracing a steady decline in attention, working memory and broader memory functions among people with iRBD.
The study tracked 162 iRBD patients – whose mean age at diagnosis was 65.6 years – for an average of 7.7 years.
A total of 318 neuropsychological assessments were analysed, and statistically significant linear declines were observed across attention/working memory and memory domains.
The most significant decline appeared in the digit symbol test, a tool used to measure processing speed, sustained attention and working memory. The test is known to be sensitive to brain damage, dementia, age and depression.
The researchers also found consistent deterioration in verbal and visual memory. These declines may appear subtle in the short term but accumulate to clinically meaningful levels over time.
All patients who had iRBD for more than 10 years experienced cognitive deterioration, even after adjusting for age and other factors.
Male patients suffered broader and deeper functional losses, with significant declines in attention/working memory and memory. Women, by contrast, showed a narrower pattern of decline, largely only showing up in teh digit symbol test, and another one involving numerical tasks.
“Gradual cognitive decline in attention/working memory and memory may represent a natural course of neurodegeneration in men with iRBD, without necessarily indicating imminent phenoconversion. Women with iRBD appeared to show greater resilience to cognitive decline compared to men,” the researchers concluded.
Professor Yoon In-young, professor of neuropsychiatry at SNUH and a member of the team, suggested gender-tailored approaches to monitor and manage symptoms.
Thirty-three subjects did not develop neurodegenerative diseases during the study period, yet they showed cognitive decline similar to those who did.
The team said the findings indicate that even among patients who manage iRBD for extended periods without progressing to dementia or Parkinson’s, gradual cognitive loss may still be underway.
They advised regular checkups and treatment for people with iRBD, even if no severe conditions have yet appeared. THE KOREA HERALD/ASIA NEWS NETWORK
