Even those who have higher chances of developing Alzheimer’s disease thanks to their DNA could protect their memory by living a healthier lifestyle, scientists concluded.  

Neurologists from China and the U.S. published their findings in the British Medical Journal on Wednesday—the results of studying 29,072 people over a 10-year period ending in 2019.

Participants were over the age of 60, with an average age of 72 years, and located in 12 provinces across China. There was an even split between men and women.

The geographical diversity created a participant pool that was representative of various degrees of urbanization, economic status, dietary patterns, and cultural and social differences, researchers said.

Those with mild cognitive impairment or dementia, life-threatening illnesses, or hearing or vision loss were not eligible to take part.

Six factors were used to investigate the association between lifestyle and memory: diet, physical exercise, socializing, cognitive activity, either never smoking or being an ex-smoker, and abstinence from alcohol.

Lifestyle information was monitored via questionnaires at the beginning of the study and at four follow-up appointments, each of which took place two to three years apart.

Healthy lifestyles for each category were defined as:

1. Diet: Daily intake of 12 food items—fruits, vegetables, fish, meat, dairy, salt, oil, eggs, cereals, legumes, nuts, and tea—were measured. Those who ate at least seven of the 12 food groups per day were considered the healthiest.
2. Exercise: The healthiest group comprised those who engaged in 150 minutes of moderate exercise or 75 minutes of vigorous exercise per week.
3. Socializing: People who took part in activities like meetings, attending parties, visiting friends or relatives, traveling, and chatting online two or more times each week were sorted into the healthiest set for socialization.
4. Cognitive activity: Reading, playing cards, playing mahjong and taking part in other games were given as examples of activities that—if engaged in at least twice a week—helped to create a healthy lifestyle.
5. Smoking: Either smoking less than 100 cigarettes in their lifetime or having quit smoking at least three years earlier.
6. Alcohol: Low-risk drinking was defined as never or occasionally drinking alcohol. Any form of daily drinking—even one gram of alcohol—pushed participants out of the healthy lifestyle category for alcohol consumption.

Based on the answers they gave, participants were sorted into three groups: “favorable” if they followed four to six of the healthy lifestyles, “average” if they engaged in two to three, and “unfavorable” if they engaged in zero or one of the healthy lifestyle factors.

During the baseline and follow-up consultations with participants, researchers measured various aspects of cognitive function, including immediate recall, short delay recall (after three minutes), long delay recall (after 30 minutes) and long delay recognition.

The test involved being read a list of 15 nouns, and then attempting to repeat as many of the words as possible.

Researchers concluded that their study provided “strong evidence that adherence to a healthy lifestyle with a combination of positive behaviors, such as never or former smoking, never drinking, a healthy diet, regular physical exercise, and active cognitive activity and social contact, is associated with a slower rate of memory decline.”

They found that living a healthy lifestyle benefited the memory even in those who were genetically more likely to develop Alzheimer’s disease thanks to possession of the apolipoprotein E ε4 allele.

“This study might offer important information to protect older adults against memory decline,” the researchers said in their paper.

However, they noted some limitations to their study, including the fact that lifestyle factors were self-reported and therefore prone to measurement errors. They also said that they were unable to tell whether lifestyle had already begun to have an impact on memory before participants enrolled in the study.