Dementia is often associated with older people, but it doesn’t just appear out of the blue.
Some risk factors may start before we’re even born, while others appear as we move through childhood and into young adulthood.
According to research, this may be the best time to start intervention.
Previous studies have identified a variety of modifiable risk factors for dementia, but changing them after neurodegeneration has set in isn’t much help, encouraging researchers to look to early life for actions that could one day make a difference.
Related: Dementia in younger people is often overlooked. Here are 5 key reasons.
A 2023 study by researchers in Sweden and the Czech Republic identified a handful of birth factors associated with a slightly increased risk of dementia later in life.
While some, such as sharing a womb with a twin, are beyond anyone’s control, others—such as shorter birth spacing and becoming pregnant over the age of 35—can influence parenting decision-making.
You can see a video summary of some of the research in this article here:
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Another study published in late 2024 looked at risk factors for younger adults aged 18 to 39. A team led by the Global Brain Health Institute (GBHI) in Ireland brought together a panel of experts from 15 countries around the world to help develop a lifelong plan to boost brain health.
“Young adulthood represents a critical window for intervention that could significantly reduce the risk of dementia later in life,” said Francesca Farina, neuroscientist at GBHI.
“To ensure healthier brain outcomes, young adults must be included as key partners in research, education, and policy-making efforts.”
Among the risk factors identified by the researchers, some are related to lifestyle, including excessive alcohol consumption, smoking, physical inactivity and social isolation.
Others are environmental, such as exposure to pollution, traumatic brain injury, hearing or vision loss, or a low level of education. And others, such as obesity, diabetes, hypertension, LDL cholesterol, and depression, are health problems that can arise from lifestyle choices.
Finally, the researchers suggest that many of the risk factors are steps we can take to reduce our risk of developing dementia, which can begin to rise much earlier in our lives than many people realize.
“Could the roots of dementia stretch back to infancy or childhood? Growing evidence suggests yes, and that exposure to risk factors in the first decade of life (or even in utero) can have lifelong implications for dementia risk,” the team explained in an article in The Conversation published earlier this year.
“Most dementia research understandably focuses on the changes associated with [age-related cognitive] decline in later life. But there is growing evidence that many of the differences in brain structure and function associated with dementia in older adults may exist at least in part from childhood.”
According to the team, there are numerous examples of this.
“In long-term studies where people have followed their cognitive ability throughout their lives, one of the most important factors explaining someone’s cognitive ability at age 70 is their cognitive ability when they were 11 years old,” the study authors explained.
“That is, older adults with poorer cognitive abilities often had these lower abilities from childhood, rather than the differences being solely due to a faster decline with older age.”
Another potential signal is evidence of brain damage or abnormalities in later life that may be related to incidents or behaviors in youth.
“Similar patterns are also seen when looking for evidence of dementia-related lesions on brain scans, with some changes appearing to be more closely related to exposure to risk factors early in life than current unhealthy lifestyles,” the authors explained.
“Taken together, perhaps the time has come for dementia prevention to be considered a lifelong goal rather than simply a focus for old age.”
In their 2024 study, some of the identified risk factors may seem obvious. Drinking and smoking, for example, are known to be harmful to health in general, and suffering a brain injury is a direct risk for later dementia.
But others take a more tortuous path – loss of hearing or sight, for example, is also linked to dementia, possibly due to brain degeneration or social isolation.
Risk factors for dementia across the lifespan. (Farina et al., Lancet Health. Longev., 2024)
Knowing the risks is one thing, but mitigating them is difficult. The researchers suggest that the problem might be best addressed by identifying factors at the individual, community and national levels.
Helping people on an individual level involves raising awareness of the importance of brain health and the risks, the team says.
This could be achieved through public health campaigns and school education, and funded by taxation of substances that adversely affect brain health, such as alcohol or cigarettes.
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At the community level, the team recommends developing an advisory board made up of diverse young adults to “function as a liaison with local governments to provide contextual knowledge about brain health in the community.”
And nationally, the group suggests creating and committing to a brain health book to keep people on track for better brain health throughout life.
“There is a real desire for young adults to learn more about their brain health – they are very aware of neurodiversity and cognition, with many identifying with diagnoses such as ADHD or autism,” said Laura Booi, GBHI social gerontologist.
“This awareness drives their strong interest in understanding and improving their brain health.”
The identified factors are not static either. The team says emerging factors need more study, including ultra-processed foods, drug use, screen time, stress and exposure to microplastics.
The research was published in The Lancet: healthy longevity.