Christine Bryden was gobsmacked in 1995, when doctors diagnosed her with Alzheimer’s. Only a year before, the 46-year-old biochemist had won Australia’s Public Service Medal for outstanding work in science and technology. “Life was up for me,” she writes on the YoungDementia UK website. “But on that fateful afternoon, everything changed, and I felt cut down in my prime.”
As she looked back, Bryden began to believe her diagnosis was somehow connected to her lifestyle. She never got enough sleep. She worked all the time. Her stress levels were stratospheric. At night she came home “with a pile of work,” which she dove into after rushing to get her young daughters settled for the night. The next morning, Bryden woke up, worked some more, then got her daughters ready for the day.
Looking at Her Lifestyle
“Maybe a lack of sleep damaged my brain to some extent. But also, a high level of stress may have contributed to my brain damage,” she writes. Bryden might not be that far off. Although doctors have been treating Alzheimer’s for decades, they are still stymied as to its exact causes. For the most part, scientists believe the disease is triggered by a number of genetic and lifestyle factors. Each impacts the brain over time. While people cannot change how old they are or the genes they are born with, they can change how they live. For starters, they can quit smoking and start eating more healthful foods. They can exercise more and lose weight. They can drink less and stimulate their minds more.
A risk factor is just that — something that increases a person’s risk, or chances, of developing some type of medical condition. Some risk factors, like age, are “non-modifiable,” which means they cannot be prevented. Others, however, may be able to change with certain lifestyle habits. Here, a look at some of the most commonly known risk factors for Alzheimer’s disease and what — if anything — you may be able to do about them.
Non-Modifiable Risk Factors
While certain memory loss is normal as we age, Alzheimer’s is not. Experts say that between the ages of 65 and 70, the prevalence of AD is 1.5 percent. That means 15 out of every 1,000 people will get the disease by that point in their life. Those odds increase with each year. By the time we reach 75, the prevalence more than doubles, to 3.5 percent, or 35 out of every 1,000. By the time we hit 80, the prevalence of AD increases to 6.8 percent. As we approach our 100th birthday, the percentage skyrockets to 44.5 percent.
Whether we get Alzheimer’s disease may have to do with our genetics. Researchers say that if one parent or sibling has the disease, your risk increases by about 30 percent. And there’s also a greater chance of developing AD if both parents are afflicted.
Some studies suggest that ethnic minorities, especially African Americans, have higher rates of dementia than Caucasians. Scientists recently identified two new genes in African Americans that may increase the risk. One of the genes, ABCA7, works to produce cholesterol and lipids. Some researchers believe that Alzheimer’s may involve abnormalities in how our bodies metabolize fat. Other factors, such as high blood pressure and diabetes, may also play a role among older African Americans and Latinos. It’s also possible that lower incomes and limited educational opportunities due to systemic discrimination against both groups contribute to the disease’s progression.
Researchers believe a traumatic brain injury increases the risk of Alzheimer’s and other forms of dementia. One study found that older adults who have had moderate traumatic brain injury (lost consciousness for more than 30 minutes) are 2.3 times more likely to develop AD than seniors who have not had a head injury. Seniors who have had severe brain injury (lost consciousness for more than 24 hours) are 4.5 times more likely to develop AD. Obviously, not everyone who experiences a head injury develops Alzheimer’s or some other type of dementia. Moreover, there is no evidence indicating that a mild brain injury increases the risk.
Modifiable Risk Factors
When it comes to Alzheimer’s, what’s bad for your heart is bad for your brain. Researchers believe that cardiovascular problems are linked to the progression of Alzheimer’s and other forms of dementia later in life. A study published in 2017 by researchers at Johns Hopkins University tracked nearly 16,000 middle-aged people in four states. Over a 25-year span, from 1987, researchers administered a variety of medical, memory, and cognitive tests. As the study progressed, 1,500 people were diagnosed with dementia, confirming that those with midlife vascular risk factors, such as diabetes or high blood pressure, had a greater chance of developing dementia. Moreover, the researchers confirmed what other studies had only hinted — smoking cigarettes increased the risk of dementia.
For years scientists have been investigating if alcohol use is related to Alzheimer’s. One study, amazingly, found that drinking up to three glasses of wine a day lowered the risk of Alzheimer’s, but only in people who have the APOE e4 gene. Other studies have also described the beneficial effects of low to moderate wine consumption. As much as researchers can decipher, low to moderate drinking actually protects the brain by reducing the viscosity, or thickness, of blood and increasing the amount of good cholesterol, known as HDL, in the body.
That said, two major reviews of multiple research studies found that heavy drinkers and binge drinkers were more likely to develop AD and other forms of dementia than those who drank moderately. Binge drinking, according to the Centers for Disease Control and Prevention, is when men consume five or more drinks in about two hours and women imbibe four or more in that same period.
Obesity causes a variety of ills, including diabetes, high blood pressure, heart problems, and other cardiovascular issues. It also seems to be a major factor in AD, doubling a person’s risk of developing amyloid plaque — the bogeyman of Alzheimer’s — later in life. Past research on how people’s weight influences their risk of dementia has produced conflicting results. Some studies say that if you’re obese, you’re at a high risk for dementia. Other studies, however, have linked lower-than-average weight to increased dementia.
In 2017, however, researchers put nearly all questions regarding obesity and Alzheimer’s to rest. A 38-year study of 1.3 million adults living in the United States and Europe concluded that individuals with a high body mass index (BMI) are more likely to develop Alzheimer’s and other forms of dementia than those who have a normal body weight.
In that same study, scientists found that people with early-onset dementia and a low BMI go on to develop full-blown dementia more often than those who are of a healthy weight. The reason, researchers concluded, is that both obesity and a low body weight during the pre-dementia stage change how the body metabolizes fat. The study suggests that maintaining a healthy weight could prevent the illness — or at least stave off its effects.
How Lifestyle May Make a Difference
In 2017, researchers in Great Britain announced that changing how you live may throw up a roadblock in the path of Alzheimer’s disease. And while there are no proven ways to permanently stave off AD, they note that some changes in lifestyle might slow its progression.
The study, conducted by the Lancet Commission on Dementia Prevention, Intervention and Care, looked at nine risk factors. It concluded that more than one-third of all Alzheimer’s cases are related to these risk factors and that avoiding them at every stage of life may delay or even stop memory loss. The researchers reached their conclusions by looking at a number of past Alzheimer’s Disease studies. Their statistical analysis found that 35 percent of dementia cases could be prevented by fully addressing these and several other contributing lifestyle issues. Researchers noted that combating Alzheimer’s needs to begin early — as soon as children start going to school.
The less time a child spends in school, the greater the risk of developing Alzheimer’s later in life. In fact, the researchers found that children who had no secondary schooling had a 7.5 percent increased risk of developing Alzheimer’s. That’s why the researchers recommend that students stay in school until they reach the age of 15.
The study also recommends that people, regardless of their age, exercise more, stop smoking, become more involved socially, reduce their weight, and manage their depression. “Although dementia is diagnosed in later life, the brain changes usually begin to develop years before, with risk factors for developing the disease occurring throughout life, not just in old age,” said lead study author Gill Livingston, Ph.D., professor of psychiatry of older people at the University College London. “We believe that a broader approach to prevention of dementia, which reflects these changing risk factors, will benefit our aging societies and help to prevent the rising number of dementia cases globally.”
The study was provocative, because researchers based their conclusions on a statistical analysis of previous studies rather than patient research. A similar study in the US was a bit more circumspect, concluding that perhaps a few lifestyle changes can bolster brain health, although the study offered no definitive proof that they would. Yet scientists are so intrigued with the lifestyle component that the Alzheimer’s Association in 2017 launched a $20 million clinical trial with 2,500 people to see whether lifestyle changes can prevent cognitive decline and dementia.
While lifestyle changes help some people, they might not help others. That’s because
there are myriad reasons that some people get Alzheimer’s and others do not. One reason is genetics, especially in early-onset cases. People who suffer from late-onset Alzheimer’s (in which symptoms become apparent in a person’s mid-60s) do so because of a series of complex brain changes that occur over decades. There is consensus among researchers that genetics, lifestyle and environmental factors all play a role.
A version of this article appeared in our partner magazine Alzheimer’s: New Hope for a Cure, in 2020.