Metabolic syndrome linked to young-onset dementia

Metabolic syndrome appears to be linked to onset of dementia before age 65, also known as young-onset dementia.

Researchers reported the findings on April 23, 2025 in Neurology.

“While most dementia is diagnosed in older age, young-onset dementia occurs while a person is still working and perhaps raising a family,” said study author Minwoo Lee, MD, PhD, of Hallym University Sacred Heart Hospital in Anyang, South Korea. “Our study found having metabolic syndrome in middle age is a risk factor for young-onset dementia.”

Metabolic syndrome is defined as having three or more of the following risk factors: excess belly fat, high blood pressure, high blood sugar, higher than normal triglycerides, which are a type of fat found in the blood, and low high-density lipoprotein (HDL) cholesterol, or “good” cholesterol.

Although metabolic syndrome is known to be a factor in late-onset dementia, its effect on young- onset dementia has been unclear. The investigators in this new study sought to determine whether metabolic syndrome and its components increase the risk of young-onset dementia, including all-cause dementia, Alzheimer disease and vascular dementia.

The researchers conducted a nationwide study using data from the Korean National Insurance Service.

Subjects (n=1,979,509) aged 40–60 who underwent national health check-ups in 2009 were included in the study, and they were followed until December 31, 2020, or age 65, whichever came first.

Covariates for which the investigators adjusted their findings included age, sex, income level, smoking status, alcohol consumption, as well as comorbidities such as hypertension, diabetes, dyslipidemia, and depression.

The primary outcome was all-cause young-onset dementia. Secondary outcomes included young-onset Alzheimer’s disease and vascular dementia.

The 1,979,509 subjects were a mean age of 49.0 years, 51.3% were male and 50.7% had metabolic syndrome.

Over an average follow-up of 7.75 years, 8,921 subjects (0.45%) developed young-onset dementia.

Metabolic syndrome was associated with a 24% higher risk of all-cause young-onset dementia, a 12.4% increased risk of Alzheimer’s disease and a 20.9% increased risk of vascular dementia.

The authors concluded, “In this large Korean cohort, MetS [metabolic syndrome] and its individual components were significantly associated with an increased risk of YOD [young-onset dementia]. These findings suggest that interventions targeting MetS may help mitigate YOD risk.”

Lee added,“Our findings suggest that lifestyle changes to reduce the risk of metabolic syndrome, such as eating a healthy diet, exercising regularly, maintaining a healthy weight, quitting smoking and reducing stress, may help reduce the risk of young-onset dementia.” Future research that follows people over longer periods of time and uses brain scans to look for biomarkers of dementia is needed to confirm and expand upon our findings.”