Studies have shown that exposure to air pollution — especially fine particulate matter or tiny droplets — increases a person’s risk of developing Alzheimer’s or other forms of dementia.

The term “cognitive reserve” refers to an individual’s ability to maintain normal cognitive function despite brain damage or pathology. It is determined by education, age, culture, genetics, and other factors.

Dr. Diana Youngman and her associates at the University of Southern California reported that individuals with high cognitive reserve are less subject to the brain damaging effects of air pollution.

In their study of more than 6,000 women ages 65 to 79, subjects were categorized according to their level of cognitive reserve based on cognitive test scores, years of education, physical activity levels, and employment status.

After 14 years of follow-up, the scientists found that women who were categorized as having lower cognitive reserve experienced a 113 percent greater environmental risk for dementia.

However, women with higher cognitive reserve had only a 21 percent increased risk from pollutant exposure.