Many people worry about dementia because they have seen its effects on parents, grandparents, or other loved ones.
Dementia can gradually steal memories, affect decision-making, and make everyday tasks increasingly difficult. As the number of older adults grows worldwide, dementia is expected to become even more common in the coming decades.
Scientists know that both genes and lifestyle contribute to dementia risk. Some risk factors cannot be changed, such as age and inherited genes.
Others, including physical activity, blood pressure, smoking, obesity, and diabetes, can often be improved through healthy choices and medical care. A key question has remained unanswered: if someone has a high genetic risk for dementia, can healthy habits still make a difference?
Researchers from Kyushu University and RIKEN recently set out to answer this question. Their findings were published in Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring.
The study involved 9,605 adults aged 65 years and older living in Japan. Researchers collected information about participants’ health, lifestyle habits, and genetic makeup. Particular attention was given to a gene called APOE ε4, which is widely recognized as one of the strongest genetic risk factors for Alzheimer’s disease.
Every person inherits two copies of the APOE gene, one from each parent. Some people inherit no APOE ε4 copies, some inherit one copy, and others inherit two copies. Previous research has shown that the risk of Alzheimer’s disease increases as the number of APOE ε4 copies increases.
The new study confirmed this pattern. People carrying two APOE ε4 copies faced a dramatically higher dementia risk than non-carriers. In fact, their risk was more than ten times greater.
The researchers then looked at lifestyle and health factors that can potentially be changed. These included conditions and behaviors linked to brain health. Participants with healthier profiles generally had lower scores for modifiable risk factors.
The results showed that healthy living was associated with a lower risk of dementia among people carrying one APOE ε4 copy and among those carrying none. This finding is encouraging because it suggests that many people can still influence their future brain health even if they have some inherited risk.
The team also used MRI brain scans to study structural changes in the brain. These scans revealed that participants with healthier lifestyles tended to have less brain shrinkage and fewer white matter lesions, which are areas of damaged tissue associated with aging, cognitive decline, and dementia.
However, the picture changed for people carrying two APOE ε4 copies. In this group, dementia risk remained high regardless of lifestyle profile. Brain scans showed substantial tissue damage and brain shrinkage whether their health habits were favorable or not.
The findings suggest that dementia prevention may not follow a one-size-fits-all approach. For many people, healthy behaviors appear capable of lowering risk. For others with extremely high genetic susceptibility, additional medical strategies may eventually be necessary.
Researchers believe these findings could help guide future prevention programs. Public health efforts aimed at controlling blood pressure, encouraging exercise, preventing smoking, and managing diabetes may still have a major impact on reducing dementia cases across the population.
At the same time, the study points toward the need for more personalized medicine. As scientists learn more about genetics, they may be able to develop prevention and treatment plans tailored to an individual’s specific risk profile.
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Source: Kyushu University and RIKEN.
