"If You Don't Sleep, Does Your Brain Shrink?"... The First Step in Preventing Dementia Is Good Sleep [Health Talk]

[Financial News] As the number of dementia patients in South Korea is expected to exceed 1 million for the first time this year, the importance of proactive prevention and early management is being emphasized more than ever.
September 21 each year is Dementia Awareness Day. It was designated as a national observance in 2011 under the Dementia Management Act to raise public awareness of dementia care and build nationwide support for overcoming the disease.
This year, in particular, the number of dementia patients in South Korea is projected to surpass 1 million for the first time. With new treatments introduced to slow the onset and progression of dementia, the importance of warm care for patients, along with proactive prevention and early management, is being highlighted more than ever.
According to the 2023 dementia epidemiological survey by the Ministry of Health and Welfare (MOHW) and the National Institute of Dementia, the number of dementia patients aged 65 and older in South Korea stood at about 970,000 last year and is estimated to exceed 1 million this year for the first time. That means about 9.25% of people aged 65 and older are living with dementia. Another figure deserves attention. The number of people diagnosed with mild cognitive impairment, which carries a high risk of progressing to dementia, was estimated at 2.98 million in 2025 and is projected to reach 4 million by 2033.
So far, there is no cure for dementia. However, drugs such as lecanemab, which remove beta-amyloid, the substance linked to Alzheimer's disease (AD), and slow the progression of the illness, have recently been introduced in South Korea. These medications can only be used in cases of mild cognitive impairment or early-stage AD, making early detection even more important. Dementia is a progressive and degenerative disease, and once it begins to worsen, it is difficult to reverse. That is why active management at the mild cognitive impairment stage is more important than managing dementia itself.
Professor Kim Jong-heon of the Department of Neurology at Korea University Ansan Hospital said, "Because dementia is a degenerative disease that is difficult to reverse once it progresses, prevention and early detection are paramount," adding, "Now that the number of dementia patients has surpassed 1 million, social interest in dementia prevention is urgently needed."

Between normal aging and dementia lies an important turning point called mild cognitive impairment. Cognitive functions such as memory, language, and judgment have declined enough to be confirmed by objective tests, but the ability to carry out daily activities is still preserved, so the condition is not diagnosed as dementia. If appropriate intervention is provided at this stage, it can delay progression to dementia or reduce the risk of developing it in the first place. That is why mild cognitive impairment is often called the golden time for dementia prevention.
However, this diagnosis does not necessarily mean dementia. The risk of progressing to dementia is higher than in healthy individuals, so early detection and management are needed. It is easy to confuse it with simple forgetfulness, but there is a way to tell them apart. With forgetfulness, a hint can help bring the memory back. In mild cognitive impairment, however, the person often still cannot remember even with a hint. If someone repeatedly forgets appointments altogether, repeats the same words, or gets lost on familiar routes, they should consult a specialist.
Professor Kim emphasized, "It is difficult to judge on your own whether it is just a lapse in memory or mild cognitive impairment," adding, "If cognitive decline is dismissed as simply a matter of age and this period is left untreated, the likelihood of developing dementia increases. Seeing a specialist and getting an accurate diagnosis is the surest way to prevent dementia."

According to recommendations from the World Health Organization (WHO), people with higher levels of cognitive activity have a lower risk of being diagnosed with mild cognitive impairment or AD. Activities that stimulate the brain, such as reading, learning foreign languages, playing musical instruments, and taking part in social activities, can help. In particular, the 2024 commission of The Lancet announced that up to 45% of all dementia cases could be prevented or delayed by managing 14 risk factors, including hearing loss, high blood pressure, smoking, obesity, depression, physical inactivity, and vision loss.
Regular physical activity is also important. Exercise directly increases blood flow to the brain and helps activate brain cell function. In particular, even a single session of aerobic exercise raises levels of brain-derived neurotrophic factor (BDNF), which is beneficial for improving brain function. Sleep management is also important. If sleep disorders persist for a long time, the brain can shrink, and beta-amyloid, which is considered a cause of dementia, accumulates in the brain. Therefore, it is best to get the recommended seven to nine hours of sleep per day. However, sleeping too long is not helpful either. If you have severe snoring, sleep apnea, or restless legs syndrome, treatment can improve sleep quality and help prevent dementia.
Professor Kim said, "Dementia prevention is not about anything special. It begins with healthy habits such as regular exercise, staying socially active, and managing vascular risk factors and hearing," adding, "If you are 60 or older, it is a good idea to get tested at a Dementia Relief Center or a neurology clinic even if you have no symptoms."
[email protected] Medical Reporter Jung Myung-jin Reporter