In a new study, researchers found having two or more chronic conditions (known as multimorbidity) in middle age is associated with an increased risk of dementia later in life.
Common chronic conditions include high blood pressure, diabetes, coronary heart disease, depression, and chronic lung disease(COPD).
The results show that the risk is greater when these sorts of conditions develop at a younger age (mid-50s) rather than later in life.
In the study, the team examined the long-term association between multimorbidity at ages 55, 60, 65, and 70 and subsequent dementia.
Their findings are based on data collected from over 10,000 British men and women taking part in the Whitehall II Study. When participants joined the study in 1985-88, they were aged 35 to 55 and were free of dementia.
For this study, multimorbidity was defined as the presence of at least two chronic conditions out of a predefined list of 13 chronic diseases, excluding dementia.
Subsequent cases of dementia were identified using hospital and death records up to 31 March 2019.
The team found multimorbidity at age 55 was linked to a 2.4-fold higher risk of dementia compared with people without any of the 13 chronic conditions.
This association weakened progressively with older age at the onset of multimorbidity.
For example, at age 65, the onset of multimorbidity before age 55 was associated with a 2.5-fold higher risk of dementia, compared with a 1.5-fold higher risk in those with the onset of multimorbidity between age 60 and 65.
In other words, for every 5 years younger age at onset of multimorbidity up to age 70, the risk of dementia was 18% higher.
When the researchers examined more severe multimorbidity (defined as three or more chronic conditions), the importance of the younger age of onset of multimorbidity for the risk of dementia was further accentuated.
For example, compared with people with no or one chronic condition, those with three or more chronic conditions at age 55 had a nearly fivefold higher risk of dementia, whereas the risk was 1.7-fold higher when the onset of multimorbidity was at age 70.
The team says given the lack of effective treatment for dementia and its personal and societal implications, finding targets for prevention of dementia is imperative.
These findings highlight the role of prevention and management of chronic diseases over the course of adulthood to mitigate adverse outcomes in old age.
If you care about dementia risk, please read studies about how to stop dementia from nose, and eye surgery may reduce dementia risk.
For more information about brain health, please see recent studies about antioxidants that may protect you from dementia, and results showing this diet could reduce your risk of cognitive impairment, dementia.
The study is published in The BMJ and was conducted by Céline Ben Hassen et al.
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