Waistline Expansion Harms the Brain: Obesity in Ages 40-45 Increases Dementia Risk by 74%

Central News Agency Report

(CNA reporter Chen Chieh-ling, Taipei, 15th) As Taiwan enters a super-aged society, the rising tide of dementia is becoming a critical public health issue. Physicians warn that a widening waistline in midlife is like adding a layer of 'fog' to the brain. A U.S. study found that overweight individuals aged 40 to 45 face a 45% higher risk of dementia, while obese individuals face a 74% increased risk.

Hsu Jung-lung,理事长 of the Taiwan Clinical Dementia Association, told CNA that dementia is not a single disease but a collective term for a group of conditions affecting brain function. It mainly includes neurodegenerative dementia (such as Alzheimer's disease) and vascular dementia. The former involves gradual damage to brain cells, while the latter is linked to poor cerebral blood flow. Overall, about 70% of dementia cases are associated with metabolic and vascular health.

Hsu emphasized that people should not underestimate the strong link between obesity and dementia risk. Studies show that for every 5-unit increase in BMI, dementia risk rises by approximately 16%. In a U.S. observational study of people aged 40 to 45, overweight individuals had a 45% higher dementia risk, and obese individuals faced a staggering 74% increase. A thickening waist in midlife means the brain is exposed to a long-term unfavorable metabolic environment.

Hsu further explained that metabolic imbalance may subject the brain to chronic vascular stress, inflammation, and insufficient energy supply. The brain requires stable blood sugar, adequate blood flow and oxygen, healthy vascular function, a low-inflammatory environment, and optimal metabolic conditions. Conditions such as obesity, diabetes, hypertension, high cholesterol, or fatty liver disease can all place the brain in a chronically adverse state.

Projections indicate that Taiwan's dementia prevalence will continue to rise—from 7.99% in 2024 to 9.95% by 2041—potentially increasing the number of dementia patients from about 350,000 to nearly 680,000. Hsu stressed that around 45% of dementia risk is modifiable. As the dementia peak approaches, early management of metabolic and cardiovascular risks is a key strategy to delay brain degeneration.

Hsu noted that dementia does not develop suddenly; pathological changes may begin accumulating 10 to 20 years before diagnosis. People often wonder whether forgetfulness is normal or a sign of dementia. The key lies in whether the symptoms are progressively worsening and affecting daily life. Typical forgetfulness includes occasionally misplacing keys or phones, briefly forgetting names or appointments, and usually recalling them when reminded—having minimal impact on daily functioning.

In contrast, dementia warning signs are repetitive and progressively deteriorating. Examples include repeatedly asking the same question within a short time, frequently losing items or placing them in wrong locations, poor sense of direction, and difficulties managing finances or scheduling medical visits. Sometimes, a sudden worsening in chronic disease control may also be linked to cognitive decline, such as forgetting to take medication, and should be closely monitored.

Dr. Tsai Meng-ju, attending physician in the Department of General Neurology at Taipei Veterans General Hospital, urged the public to start dementia prevention now. Brain health is about 'seeking benefits and avoiding harms.' 'Seeking benefits' involves enhancing brain-protective factors, including mental stimulation, physical exercise, social engagement, maintaining a healthy weight, and adopting a Mediterranean-style diet.

'Avoiding harms' means reducing dementia risk factors. Dr. Tsai warned that smoking, brain injuries, depression, hypertension, high blood sugar, high cholesterol, and even hearing loss may increase dementia risk. If individuals or their families notice memory decline, they should seek medical help promptly, as early medical intervention can slow disease progression. (Edited by Chen Ching-fang) 1150615