Many of us have heard that doing activities like puzzles, playing Sudoku or chess can help stimulate our brain and prevent memory loss, but how many puzzles do we have to do or how many days a week should we have to play chess for it to be useful in the long term?

Although the answers to these questions do not yet exist, we are getting closer to knowing what lifestyle adjustments we can adopt to prevent age-related cognitive decline and reduce the risk of dementia.

“Dementia and cognitive impairment are multifactorial,” says George Rebok, Professor Emeritus at the Department of Mental Health and the Department of Psychiatry at the Johns Hopkins Bloomberg School of Public Health. “There is a push for multi-component interventions that involve not just cognitive training, but also dietary practices, good sleep hygiene, exercise, managing your vascular risk factors, and so on.”

Rebok has studied these pathologies for decades and developed interventions to prevent them, which, broadly speaking, have lasting effects on the cognitive abilities of older and middle-aged adults.

Building community also seems to be key. “A lot of times, as people get older, they become more isolated,” says Margaret Flanagan, researcher and professor at the University of Texas Health Science Center. “So trying to stay engaged, whether it’s a book club or getting together with friends once a week is important”.

Lessons from the Nun Study

One of the milestones that has helped us understand how to protect our cognitive abilities against the inevitable passage of time is the Nun Study, a long-term research project that examines aging and dementia in a group of Catholic nuns.

It began in the late eighties when neurologist and researcher David Snowdon met the group of School Sisters of Notre Dame, in a convent in Minnesota.

All of them –almost 700 nuns– agreed to be studied over the years and to donate their brains to science once they passed.

“They all lived in such a controlled and homogeneous environment that would be pretty impossible to get outside of a laboratory,” says Flanagan, who now leads the study.

These conditions allowed researchers to exclude confounding factors and truly understand the impact of certain behaviors and habits on cognition.

Today, all the nuns have passed away and their brains are still being actively analyzed.

Among the many findings that have been made thanks to them is the importance of education and comorbidities, specifically vascular diseases, for the prevention of dementia or for maintaining cognitive skills despite suffering from it.

Density of Ideas and a Life With Meaning

Of the nuns enrolled in the study, most were between 70 to 100 years old. Some showed a lack of memory and reasoning skills, while others had them intact.

What is impressive is that some nuns had damaged brains, with an excessive accumulation of beta amyloid and tau plaques –proteins that amass in the brain and have been associated with the onset of Alzheimer’s– but they still retained their cognitive abilities.

Researchers found they had protective factors that may promote healthy aging in others.

These include density of ideas –the amount of concepts and information present in a person’s speech or writing– and a complex vocabulary: the sisters who had a more extensive vocabulary had significantly less clinical dementia.

“They also had less coexisting pathologies,” Flanagan explains. “Specifically, less TDP-43, a protein that accumulates in Parkinson’s disease in the midbrain.”

Thus, the total burden of disease can predict whether or not a person will develop dementia in the future.

In addition, most of the nuns with good cognitive skills did not smoke, had constant physical activity, less stress, and close social relationships.

The importance of this becomes clear when comparing the Nun Study with the Honolulu-Asia Aging Study (HAAS), a longitudinal study of men of Japanese descent in Hawaii investigating aging and age-related diseases.

In HAAS, the prevalence of dementia is higher than in the Nuns’ study, and one of the explanations is that the men smoked more and had more vascular diseases.

“Spirituality and religion, in the case of the sisters, provided a strong foundation for a positive outlook towards life,” Flanagan says. “So having meaning and a spiritual connection, whatever your religious preference, seems to be a protective factor.”

What Does the ACTIVE Study Reveal About Cognitive Decline and Independence?

Beyond ensuring we maintain healthy lifestyle habits, there are programs that can help counteract the cognitive decline that comes with age. One example is the ACTIVE study, a long-term research project that analyzed how different types of cognitive training impact mental abilities in older adults.

The program consisted of a sort of school for this sector of the population, to which they attended in groups of three to five people, and included three types of cognitive training: memory, reasoning, and processing speed.

It consisted of ten sessions, up to 75 minutes each, implemented over a period of less than six weeks. Some participants were offered follow-up sessions months or even years later.

“For speed and reasoning interventions, there were effects that lasted ten years,” says Rebok, one of the study leaders.

These effects included a lower incidence of cognitive decline, compared to those who did not receive the treatment, as well as greater independence in performing daily tasks, such as administering medications, managing finances, cooking, and driving.

Although these types of interventions cannot prevent dementia on their own, they can help maintain cognitive function and quality of life in older people.

“For cognitive training to work, all these other factors, a healthy diet and such, have to be in place,” says Rebok. “It’s important to start early, but even in your late seventies, eighties or nineties, even if you haven’t done a lot of this stuff, it’s never too late to start.”

The Future of Dementia Prevention

Thinking ahead, the field of dementia prevention promises great advances as it becomes increasingly clear that a multifactorial approach is required, involving interventions in multiple areas.

“There’s no cognitive vaccine out there so you won’t get dementia,” Rebok emphasizes. However, we know that maintaining a healthy lifestyle, which includes not smoking, eating a balanced diet, sleeping well, exercising, and managing comorbidities as much as possible, is essential to preventing cognitive decline.

Having high blood pressure, as well as elevated levels of cholesterol and blood glucose, have a strong correlation with the onset of dementia.

“Managing stress and mental health is probably also key,” summarizes Angelique Gonzalez, researcher and research assistant to Dr. Flanagan.

The scientists also emphasize the importance of education and socialization, especially for vulnerable or discriminated people.

“Equity is critical,” Rebok says. “We don’t want to design interventions that exacerbate or create more disparities.”

With all this and the arrival of cutting-edge technologies, such as spatial transcriptomics –a technique that maps the gene expression of an entire tissue– Artificial Intelligence (AI) and new biomarkers, the day when dementia ceases to exist in humans could be closer than we think.

“I’m working on developing a test that could tell a person their combination of brain pathologies decades before the symptoms onset,” Flanagan says. “Treatments could be given to that person right away and eventually there would be no dementia, that is my dream.”

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