Dementia is a broad term used to describe a decline in mental ability that is severe enough to interfere with daily life. It is not a specific disease, but rather a group of symptoms caused by various diseases or conditions. Some of the most common types of dementia include Alzheimer’s disease, vascular dementia, dementia with Lewy bodies, and frontotemporal dementia. As the global population ages, dementia is becoming an increasingly common condition. According to the World Health Organization, around 55 million people were living with dementia in 2019, and this number is projected to rise to 78 million by 2030 and 139 million by 2050. Given the huge impact dementia has on individuals, families, communities, and health care systems, understanding key risk factors for dementia is crucial for developing preventive strategies.
What are the risk factors for dementia?
There are a number of factors that can increase a person’s risk of developing dementia. Some of the most well-established risk factors include:
Age
Advancing age is the strongest known risk factor for dementia. The risk doubles every 5 years after age 65. After age 85, the risk reaches nearly one third. As people get older, changes accumulate that can cause dementia, including the buildup of abnormal proteins and loss of connections among nerve cells in the brain.
Genetics
Certain genes can increase the likelihood of developing Alzheimer’s disease and other types of dementia. For example, inheriting one or two copies of the apolipoprotein E (APOE) ε4 allele increases risk substantially, especially if the gene is inherited from both parents. Other genes associated with Alzheimer’s disease and frontotemporal dementia have also been identified. However, genetics alone does not determine whether someone will develop dementia.
Cardiovascular health
Heart health and dementia are closely connected. Many of the same factors that damage the heart, like high blood pressure, high cholesterol, and diabetes, also increase the risk of dementia. Poor cardiovascular health leads to constricted blood vessels and impaired blood flow in the brain. Experiencing a stroke also raises dementia risk.
Education and cognitive activity
People with lower levels of education and cognitive activity tend to have higher dementia risk. It is believed that continuing to challenge your brain throughout life builds cognitive reserve that helps prevent or delay dementia symptoms. Higher educational attainment may reflect this, while cognitive inactivity allows skills to deteriorate.
Traumatic brain injury (TBI)
A history of moderate to severe TBI, like concussions, can increase dementia risk, especially if the injuries resulted in loss of consciousness. TBI appears to trigger gradual damage to the brain that eventually leads to the development of chronic traumatic encephalopathy (CTE), a dementia-like condition.
Diet
An unhealthy diet high in saturated fats and simple carbohydrates can increase dementia risk. Meanwhile, a Mediterranean diet high in fruits, vegetables, whole grains, and unsaturated fats seems to be protective against dementia. Certain nutrients like omega-3 fatty acids and antioxidants support brain health as well.
Physical inactivity
Evidence suggests that physically inactive individuals have a greater risk of dementia than active individuals. Regular exercise may protect the brain by improving blood flow, reducing inflammation, and supporting the growth of new neurons. However, extremely high levels of physical activity have conversely been linked to increased dementia risk.
Smoking
Smoking damages blood vessels and can lead to vascular dementia by depriving the brain of oxygen. Smokers have up to a 79% greater risk of developing Alzheimer’s disease as well. Quitting smoking, even later in life, can reduce dementia risk compared to those who continue to smoke.
Loneliness and social isolation
A lack of social connections and feelings of loneliness are emerging as notable risk factors for dementia. Social activity and interaction seem to help build cognitive reserve and resilience against dementia. People who feel lonely or isolated tend to have higher blood pressure, more depression, and more stress as well, which all elevate dementia risk.
Hearing loss
Hearing impairment is independently associated with accelerated cognitive decline and dementia. When the ears cannot properly transmit sound to the brain, the brain undergoes changes that result in thinking and memory problems over time. Treating hearing loss through devices like hearing aids may help prevent dementia.
What is the strongest risk factor for dementia?
Of all the identified risk factors, age is by far the strongest. According to population attributable risk estimates, advanced age accounts for the largest proportion of dementia cases worldwide. While some degree of cognitive decline is normal with aging, dementia is not an inevitable consequence. Still, age remains the top risk factor, with a doubling in incidence occurring every 5 years after 65. Genetics also play a substantial role by determining the brain’s baseline resilience. However, many genetic factors are not yet modifiable. Other major risk factors like heart health, education, and physical activity can be altered through lifestyle changes and preventive healthcare. Avoiding or reducing key modifiable risk factors, combined with lifelong learning and social engagement, provide the best strategy for preventing dementia, especially for older adults. Though some cognitive change will occur, a healthy lifestyle maximizes the chances of aging with cognitive health into the latest stages of life.
Prevention strategies
Because advanced age is such a key risk factor for dementia, delaying onset through prevention is crucial. Some tips to keep the brain healthy and lower dementia risk include:
Heart health
– Get blood pressure and cholesterol checked regularly. Work with your doctor to control high blood pressure and high cholesterol.
– Eat a heart-healthy diet low in salt and saturated fat. Include plenty of fruits, vegetables, and whole grains.
– Stay physically active with at least 150 minutes of moderate exercise per week.
– Reach and maintain a healthy body weight.
– Don’t smoke. If you do smoke, quitting can still lower dementia risk.
– Manage other health conditions like diabetes, depression, and hearing loss.
Brain health
– Engage in lifelong learning. Take classes, learn new skills, read books, do puzzles.
– Be socially active. Have regular contact with friends and family.
– Try brain training exercises like memory games and problem-solving activities.
– Challenge your mind by doing everyday tasks in new ways, like brushing your teeth with your non-dominant hand.
– Stick to a routine and use memory aids like calendars, to-do lists, and reminders.
– Get enough sleep and find ways to reduce stress.
– Eat a Mediterranean-style diet with more fish, poultry, fruits, vegetables, nuts, and olive oil.
– If you drink alcohol, do so in moderation.
Safety and preventive care
– Wear seatbelts and take steps to prevent head injuries.
– See your doctor if you experience memory concerns, confusion, or thinking changes.
– Discuss your family history and any dementia risk factors with your doctor.
– Have regular eye exams to check vision. Vision problems can contribute to dementia risk.
– Get your hearing checked and treat any hearing loss.
– Ask your doctor if taking a daily aspirin to prevent stroke and heart attack may be appropriate for you.
Conclusion
Advanced age remains the strongest known risk factor for dementia given the accumulation of changes and damage occurring in the aging brain over time. However, a number of modifiable risk factors also substantially influence a person’s likelihood of developing dementia. Making healthy lifestyle choices and managing health conditions can help build cognitive reserve and delay the onset of irreversible cognitive decline. While some degree of mental decline is expected with normal aging, maximizing prevention strategies allows more people to retain cognitive health into old age. Dementia is not an inevitable result of aging. Understanding key risk factors provides vital information for lowering individual risk and reducing the overall burden of dementia.