Can poor sleep increase dementia risk and what are its early signs? New study reveals hidden risks

Poor sleep has often been linked to a large share of dementia cases. About 13% of dementia cases may have roots in insomnia, a recent study on older adults in the US found.

However, another study from the Sleep and Dementia Consortium, which followed 4,600 adults for up to 19 years, found that the amount of time spent sleeping does not correctly predict who will develop dementia.

A sleep researcher, quoted by the South China Morning Post (SCMP), noted that sleep is certainly important – it affects our work, relationships, immunity, and even our appetites.

Sleeping, the researcher said, is when the brain goes about housekeeping, clearing it of the toxic proteins that are hallmarks of Alzheimer’s disease.

However, it might not be poor sleep itself that affects the brain, but specific sleep disorders, noted Christine Walsh, an associate professor of neurology at the University of California’s Memory and Ageing Centre.

What is the specific sleeping disorder associated with dementia?

Sleep apnoea, common in adults over 50, is the most common sleeping disorder associated with dementia, the SCMP report quoting Walsh said.

In this sleep disorder, breathing repeatedly stops or becomes shallow while you are asleep, then resumes seconds later.

Each time, the brain briefly awakens you to restart breathing, fragmenting the deep and REM sleep, and preventing long, restorative sleep cycles.

Sleep apnoea also affects the heart -- it causes blood oxygen to drop, leading to a surge in carbon dioxide hundreds of times a night, which in turn triggers adrenaline bursts that spike blood pressure and heart rate.

It is also strongly associated with increased inflammation in the body, and arrhythmias – irregular heartbeats – especially atrial fibrillation, which has a proven link with dementia.

Another sleeping disorder that can affect the brain is REM sleep behaviour disorder. In this very rare disorder, sufferers act out dreams. The SCMP report noted that this condition is an early sign of abnormal protein processes that drive Parkinson’s disease and Lewy body dementia.

What are the early signs of dementia?

Change in walking and balance

Walking and balancing are two of the major strengths and abilities humans have, said Timothy Kwok, a professor of geriatric medicine at the Chinese University of Hong Kong, according to SCMP.

These abilities are entirely dependent on healthy brain function. “When dementia sets in, steps become uneven and smaller, thus increasing the risk of falling,” he said.

Swallowing becomes hazardous

Swallowing is a complex motor skill managed by the brain. In moderate to late stages of dementia, chewing and swallowing become problematic, a condition known as dysphagia, Kwok noted.

“Initially, people with dementia chew less and may spit food out instead of swallowing it. Later, swallowing becomes difficult and uncoordinated. Liquid is more difficult to swallow than solids,” he said.

Memory test is not enough

Often, clinics test cognition in older people with a focus on memory and verbal responses. However, the SCMP report citing research said that it is important to consider a person’s whole health when trying to ascertain their brain health.

It is because women often have stronger verbal skills than men, which can hide early dementia symptoms.

Loss of bladder control

When dementia sets in, the bladder becomes irritable, Kwok said, resulting in urinary frequency.

As the disease advances and dulls the sensation, it becomes less noticeable, and the ability to hold in urine is impaired. Later, faecal incontinence follows too.

Impaired sleep

Dementia impairs one’s ability to fall asleep and to maintain sleep, said Kwok, which leads to further cognitive decline.

Sleep helps remove toxic waste, such as beta-amyloid protein, from the brain and helps consolidate memory.

However, some dementias lead to excessive sleep.