New Delhi: People who do not have high blood pressure or diabetes and do not smoke may remain free from dementia for nearly 13 years longer than those with all three risk factors, according to findings from a long-term study in the United States.
The study, based on data from the Atherosclerosis Risk in Communities (ARIC) Study, examined the relationship between three major vascular risk factors in midlife — hypertension, diabetes and current smoking — and the subsequent risk of dementia.
Researchers followed 12,409 adults for a median period of 26.3 years to assess how these factors affected dementia-free life expectancy. The findings indicate that maintaining better cardiovascular and metabolic health during midlife may have substantial benefits in later life.
Dementia-free years linked to vascular risk
According to the study, participants who had none of the three risk factors were estimated to live an average of 30.1 years without developing dementia from the age of 55.
In comparison, those who had all three risk factors — high blood pressure, diabetes and current smoking — had an estimated dementia-free period of 17.5 years from age 55.
This represents a difference of about 12.6 years, or nearly 13 years, in the estimated period lived without dementia.
The researchers also found a progressive relationship between the number of risk factors and dementia-free life expectancy. Participants with one of the three risk factors were estimated to remain dementia-free for around 26.3 years from age 55. Those with two risk factors had an estimated dementia-free period of approximately 21 years.
The findings suggest that the accumulation of vascular risk factors may be associated with a substantially shorter period of life without dementia.
Risk rises with multiple factors
The study also found a significant increase in dementia risk among people with multiple vascular risk factors.
Compared with participants who had none of the three risk factors, individuals who had all three were found to have a 2.69-fold higher risk of developing dementia.
Their risk of dying without developing dementia was also reported to be 5.61 times higher than that of participants without the risk factors.
The effect became more evident as participants grew older. Among people with all three risk factors, the estimated risk of developing dementia increased from 23% at the age of 55 to 37% at 75.
By the age of 85, only 7% of those with all three risk factors were estimated to remain free from dementia. In contrast, 35% of those without any of the three risk factors were estimated to remain dementia-free at that age.
The findings highlight the potential importance of addressing vascular health well before older age, when the risk of dementia generally becomes more prominent.
Modifiable risks offer scope for prevention
High blood pressure, diabetes and smoking are among the risk factors that can potentially be modified through medical care and lifestyle changes.
Hypertension can damage blood vessels over time and is associated with an increased risk of several cardiovascular and neurological conditions. Diabetes can similarly affect blood vessels and other systems in the body, while smoking contributes to vascular damage and a range of chronic diseases.
The study’s findings therefore reinforce the importance of identifying and managing these conditions during midlife rather than waiting until old age.
Maintaining blood pressure and blood sugar within recommended ranges, avoiding tobacco and following a physically active lifestyle are among the measures that can contribute to better overall cardiovascular health.
Global focus on dementia prevention
The study comes amid increasing international attention on the possibility of preventing or delaying some cases of dementia by addressing modifiable risk factors.
Updated global recommendations from the World Health Organization have highlighted the potential contribution of risk-factor management to dementia prevention. The guidance has stated that up to 45% of dementia cases could potentially be prevented or delayed by addressing modifiable factors.
Along with controlling high blood pressure and diabetes and stopping smoking, recommended measures include maintaining regular physical activity and reducing exposure to air pollution.
These approaches are particularly relevant because vascular health and brain health are closely interconnected. Conditions that affect blood vessels can also influence the supply of blood and oxygen to the brain.
Long-term benefits of midlife intervention
The ARIC findings provide further evidence that health decisions made during midlife may influence outcomes decades later. Rather than focusing only on dementia treatment after symptoms emerge, the findings point towards the potential value of prevention and risk reduction earlier in adulthood.
The researchers emphasised that managing cardiovascular and metabolic health earlier in life could have long-term benefits, including potentially extending the period people live without dementia.
However, the presence or absence of these three risk factors does not determine an individual’s future with certainty. Dementia has multiple causes and risk factors, including age, genetics and other health and environmental influences.
The study nevertheless underscores a practical message: controlling high blood pressure and diabetes and avoiding smoking can contribute not only to cardiovascular health but may also be associated with a longer period of life free from dementia.
As populations age and dementia becomes an increasing public health concern, greater attention to preventable risk factors during midlife could play an important role in reducing the burden of the disease.
