In their article, “Long-term exposure to air pollution and trajectories of cognitive decline among older adults,” Dr. Kulick and colleagues1 examined the association between exposure to longterm air pollution and cognitive decline in older adults living in New York City.
How was the study done? Dr. Kulick and colleagues looked at 2 groups of people living in northern Manhattan. The 2 groups are involved in 2 different studies examining factors that affect health in adults living in New York City. In one group (Washington Heights–Inwood Community Aging Project [WHICAP]), the goal of the long-term study is to better understand the relationship between aging and dementia. The second group (Northern Manhattan Study [NOMAS]) is enrolled in a study that evaluates cardiovascular risk factors and health in a multiethnic urban setting. In order to be enrolled in the studies, a person could not have dementia. In other words, these were people who had no cognitive problems when they entered into the trials. For the purposes of this study, there were 5,330 people in the WHICAP study. There were 1,093 in
the NOMAS group. With regards to air pollution and cognitive decline, each group was analyzed separately.