Medical programs designed to prevent dementia are increasingly focusing on specific combinations of risk factors. However, it is not clear which combinations of changeable risk factors should be targeted to achieve the best results. This study aimed to find the risk factor combinations that are both most common and have the most negative effect on thinking skills. The researchers also looked at how these risk factors interact with each other.
The research involved a three-year analysis of data from the Canadian Longitudinal Study on Aging, which included 30,097 adults aged 45 to 85 living in the community. The study identified the most common combinations of two, three, and four risk factors out of a list of 12 that can be modified. Changes in participants' thinking skills were measured over the three years using a combined score from a series of mental tests.
Researchers found that the combination of two risk factors that was both very common and had the most negative effect on overall thinking skills was hearing loss and physical inactivity. For combinations of three factors, the most detrimental group was hearing loss, physical inactivity, and high blood pressure. For four factors, the combination was hearing loss, physical inactivity, high blood pressure, and sleep disturbance. Similar results were seen when looking specifically at memory and at executive functions, which are skills like planning and problem-solving.
The study also found a specific interaction between hearing loss and physical inactivity. The combined negative effect of these two factors on thinking skills was greater than the sum of their individual effects. This suggests they work together to worsen cognitive health.
The study concluded that the combined effect of multiple risk factors on brain health depends on the specific combination. The findings suggest that targeting hearing loss and physical inactivity together could offer a greater potential benefit than targeting other pairs of risk factors. High blood pressure and sleep disturbance can also be included for programs targeting three or four risk factors. The authors state that hearing health and exercise should be priorities for prevention programs that target multiple risk factors.
