A large international study has found that when older adults have both physical frailty and depression, their risk of developing dementia rises sharply.
The researchers believe that these two conditions together may account for about 17% of the overall risk of dementia. The study was published in the open access journal General Psychiatry.
Right now, around 57 million people worldwide are living with dementia. That number is expected to triple by the year 2050. Scientists have long known that both frailty and depression are linked to a higher risk of dementia.
But most past studies only looked at each factor by itself. This new research aimed to find out what happens when both frailty and depression occur together.
The study followed 220,947 people from three major studies: the UK Biobank, the English Longitudinal Study of Aging (ELSA), and the Health and Retirement Study. The average age of the participants was 64, and 53% were women. None of them had dementia when the study began.
To measure frailty, researchers used criteria such as unintentional weight loss, tiredness, low activity, slow walking, and weak grip strength. People with three or more of these signs were considered frail. Depression was measured using mental health questionnaires and hospital records.
Frail participants were generally older, more likely to be women, had more health problems, weighed more, and had lower levels of education than those in better physical health.
Over nearly 13 years of follow-up, 9,088 participants were diagnosed with some form of dementia. This included 7,605 from the UK Biobank, 1,207 from the Health and Retirement Study, and 276 from ELSA.
The findings were striking. People who were physically frail were more than two and a half times as likely to develop dementia as those who were not frail. People with depression had a 59% higher risk.
But those who were both frail and depressed were over three times more likely to be diagnosed with dementia compared to people who were in good physical and mental health.
The study also showed that the combination of frailty and depression had a stronger impact on dementia risk than either condition alone. About 17% of the total dementia risk in the study population was linked to the combined effect of these two factors.
The researchers explained that when someone has only one of these problems, the body and brain may be able to cope. But when both are present, it becomes harder for the body to manage, and the risk of dementia rises sharply.
It’s important to note that this was an observational study, so it can’t prove that frailty and depression directly cause dementia. Also, the way frailty, depression, and dementia were defined varied between the different study groups.
Still, the researchers say the findings are important. Because both frailty and depression are treatable, there is hope. Taking steps to improve physical strength and mental health in older adults may help reduce the chances of developing dementia.
If you care about brain health, please read studies about inflammation that may actually slow down cognitive decline in older people, and low vitamin D may speed up cognitive decline.
For more health information, please see recent studies about common exercises that could protect against cognitive decline, and results showing this MIND diet may protect your cognitive function, prevent dementia.
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