Harmful lifestyle habits can significantly increase the likelihood of developing Alzheimer's disease Physical inactivity or sedentary lifestyles, sleep disturbance or poor sleep quality, malnutrition, unhealthy diet, obesity, tobacco and alcohol use, among others, can increase the accumulation of toxic proteins, reduce cognitive reserve, induce diabetes and cause cognitive decline, thus increasing the risk of Alzheimer's disease. While ageing and gender are non-modifiable risk factors for dementia, other factors can be reduced or avoided, accounting for up to 45% of the odds of developing late-onset or sporadic Alzheimer's disease.

The new study published in The Lancet reviews modifiable risk factors for sporadic Alzheimer's disease, providing a large epidemiological study that supports these factors and their intervention. Twelve of them were already known, such as brain contusions, hypertension, diabetes, hearing loss, depression, social isolation and even air pollution. In addition, two new risk factors not previously considered have been included: vision loss and high cholesterol levels.

Changes in lifestyle habits are recommended as early as possible to prevent or even improve the clinical symptoms of Alzheimer's, as these actions also benefit general health. It should be noted that prevention and interventions should not only be carried out by the individual, but also [should] be supported by governmental policies at local and international level, targeting high-risk groups.

This study by Livingston and colleagues is an excellent up-to-date analysis of the research from around the world examining risk factors for developing dementia.  The data in the paper add compelling evidence for the ability to prevent dementia by addressing some of the 14 identified risk factors.  This type of research cannot conclusively link any of these factors directly to dementia, but contribute to the growing evidence that a healthy lifestyle including keeping your brain engaged through education, social activities,  exercise, and cognitively stimulating activities, and avoiding things like head injury and factors that are bad for your heart and lungs can boost brain resilience and prevent dementia.  There are new links in this report with vision loss and high cholesterol associating with dementia risk, which broadly fit with the previous research indicating that keeping your brain active and avoiding vascular risk factors that come with a sedentary lifestyle and poor diet is good for reducing dementia risk. 

This study is important as it gives insight into ways that both individuals and governments can help reduce dementia risk. It also helps guide more fundamental neuroscience research into how these factors influence brain vulnerability to the diseases that cause dementia. While this excellent study estimates that up to half of dementia cases could be prevented by changing modifiable risk factors, it is important that we keep in mind that the other half of people with dementia likely developed brain disease for unavoidable reasons related to factors beyond their control like genetics. 

A new study suggests that nearly half of the world's dementia cases could be preventable. The new report from the Lancet Dementia Commission updates the available scientific evidence on modifiable risk factors for dementia and adds two new factors to the list of twelve already known. The report states that 45% of dementia cases worldwide could be prevented if these risk factors were eliminated.