Although genetics plays a role in the development of Alzheimer’s disease and other types of dementia, lifestyle factors are also involved. One recent study found, for example, that even people with a high genetic risk were about a third less likely to develop dementia if they followed a healthy lifestyle than if they didn’t.
But which specific lifestyle factors are the ones most likely to affect the chances of developing the disease? To try to answer that question, an international team of researchers analyzed 396 previous studies, including 153 randomized controlled clinical trials, considered the “gold standard” of research. Collectively, these studies had investigated more than 100 possible modifiable risk factors for dementia. Based on that evidence, the team identified 10 factors as being most likely to increase the chances of having dementia late in life.
The researchers published their findings earlier this month in the Journal of Neurology, Neurosurgery & Psychiatry. The 10 factors they identified, and quick explanations for why each appears to be associated with a higher risk, are listed below.
(Note: Although all these factors are considered “modifiable,” that doesn’t mean individuals can change all of them. Older adults can’t alter how much schooling they received early in life, for example. Nor is reducing stress easily attainable for many people, such as those living in poverty or caring at home for a sick loved one with a serious, debilitating illness.)
Diabetes has long been considered a risk factor for dementia. Scientists aren’t sure why, but it’s believed that excess glucose (sugar) in the blood — which happens when diabetes is uncontrolled — damages the brain over time.
The new study says people should be encouraged to avoid developing type 2 diabetes by adopting healthier lifestyles. It also urges those who already have diabetes to be closely monitored by their doctors for signs of cognitive decline.
Homocysteine is an amino acid that is produced in the body when proteins are broken down. A high level of these amino acids — a condition known as hyperhomocysteinemia — can damage the arteries and lead to blood clots. Two decades ago, it was reported that people with dementia often had elevated blood levels of homocysteine. Since then, some research has suggested that lowering homocysteine levels might protect against cognitive decline.
The new study suggests that older people should have their blood regularly checked for its homocysteine level and that those with high levels should be treated with vitamin B and/or folic acid.
- Body mass index (BMI)
Being overweight or obese before the age of 65 is associated with an increased risk of developing dementia later in life. Adults should maintain a healthy weight — a BMI of between 18.5 and 24.9 — throughout adulthood, the current study says. The study also stresses, however, that people should not be “too skinny.” The risk of dementia is also elevated for individuals who are underweight (a BMI of less than 18.5) in middle age and in later life.
The effect of education on the risk of dementia has been controversial. Several studies have found an association between a high level of education and a low risk of dementia. Some researchers believe, however, that such findings simply reflect the ability of highly educated people to better compensate for the effects of dementia. The new study recommends that people receive as much education as possible early in life.
- High blood pressure in midlife
Quite a bit of research has linked high blood pressure (hypertension) in midlife (ages 40 to 64) with dementia later in life. It’s particularly associated with vascular dementia, which is caused by a reduced flow of blood in the brain. Uncontrolled high blood pressure can impede that flow by damaging blood vessels. Some research has found that treating high blood pressure reduces the risk of dementia. The new study says people under the age of 65 should avoid high blood pressure by following a healthy lifestyle.
- Orthostatic hypotension
Orthostatic hypotension is a condition in which a person experiences a sudden drop in blood pressure when they stand after sitting or lying down. The low blood pressure results in less oxygen and nutrients flowing to the brain, and, over time, may increase the risk of dementia. The new study suggests that doctors closely monitor individuals with orthostatic hypotension for signs of cognitive decline.
- Head trauma
Over the past 30 years, researchers have linked head trauma, such as a concussion, with dementia later in life. Older adults with a history of moderate head trauma are 2.3 times more likely to develop Alzheimer’s disease than their peers without that history, although, as the Alzheimer’s Association points out, it’s not clear if a single or repeated head injures are needed to create that level of risk. The new study calls on people to protect their head from injuries.
- Cognitive activity
Evidence suggests that people who keep their brains active — by reading, playing a musical instrument or taking adult education classes — are less likely to develop dementia. Such activities may help strengthen the synaptic connections between brain cells — connections that are known to break down with dementia. The new study recommends that people engage in mentally stimulating activities throughout their lives.
Research has suggested a link between chronic stress and dementia, although the reasons for it are unknown. Stress is known, however, to affect the body’s immune system, which plays a role in the development of dementia. In addition, high levels of the “stress hormone” cortisol are associated with memory problems. The new study recommends that people learn how to avoid daily stress as much as possible and learn how to relax the mind.
Depression is common among people with dementia, although it’s unclear if the depression causes the dementia or is instead a sign of the disease. Research suggests, however, that depression can lead to chemical changes in the brain that damage brain cells. The new study urges people to take steps to maintain good mental health.
FMI: The Journal of Neurology, Neurosurgery & Psychiatry is an open-access publication, so you can read the study in full on its website.