While we are still finding new risk genes, genetics alone cannot for the 98% of sporadic cases of late-onset Alzheimer’s disease. As scientists we believe that the risk of developing Alzheimer’s comes from a combination of genetics, lifestyle and environmental factors, rather than a single cause.
There are certain environmental factors that are suspected to increase the risk of developing Alzheimer’s, with some studies showing a link to air pollution from car exhaust fumes, for example. The potential risk from environmental factors for developing Alzheimer’s and other chronic diseases, has always interested me. Long before I became an Alzheimer’s scientist, I questioned for example, the impact of the industrial chemicals that find their way into our waterways, air supply, food sources, and ultimately into our own body tissue. What effect did their bioaccumulation have on our health?
Indeed, the effects of exposure to inorganic and organic hazards, pesticides, industrial chemicals such as flame retardants and air pollutants on our health has been under investigation through epidemiological studies for many years. Studies have for example looked at how these exposures affect a growing foetus in utero, and after birth during a child’s growth and development through into adulthood, to try and understand how it could potentially increase the risk of Alzheimer’s in later life.
Chemical exposure is just one of a range of very diverse environmental factors. Broadly speaking, environmental factors are anything that affects living organisms. Examples therefore include diet, exposure to toxins, pathogens, radiation, chemicals found in personal-care products and household cleaners, stress and even mental and physical abuse. All these factors could in isolation or through bioaccumulation act as a trigger to develop disease.