Using an air purifier may improve brain function in adults over 40.

Particulate matter such as PM2.5, soot, and dust floating in the air is said to be linked not only to respiratory and cardiovascular diseases but also to neurological disorders such as Alzheimer's disease and Parkinson's disease. As air purifiers equipped with HEPA filters are used as a means to reduce such particulate matter, Nicholas Pellegrino and colleagues at the University of Connecticut studied how the results of brain function tests change after using an air purifier equipped with a HEPA filter for one month.

Effect of HEPA filtration air purifiers on cognitive function from a secondary outcome analysis of a pragmatic randomized crossover trial | Scientific Reports

https://theconversation.com/hepa-air-purifiers-may-boost-brain-power-in-adults-over-40-new-research-280885

HEPA stands for 'High Efficiency Particulate Air,' and refers to a high-performance filter that captures fine particles in the air. Air purifiers equipped with HEPA filters are used to remove particulate matter such as PM2.5, soot, and dust from the air, but Pellegrino et al. say there are not many studies that have investigated how using air purifiers equipped with HEPA filters affects human cognitive function.

Therefore, Pellegrino and colleagues investigated the effects of using HEPA-equipped air purifiers on cognitive function in 119 people aged 30 to 74 living in Somerville , Massachusetts. Somerville is located near two major roads, 'Interstate 93' and 'Route 28,' and is an area susceptible to air pollution from automobile exhaust and other sources. For this reason, it was considered a suitable location to study how using air purifiers affects health.

byBrian Corr

Pellegrino et al. divided the experiment participants into two random groups. One group used an air purifier equipped with a HEPA filter for one month, followed by a one-month break, and then used an air purifier without the HEPA filter for one month. The other group, conversely, used an air purifier without the HEPA filter for one month, followed by a one-month break, and then used an air purifier equipped with a HEPA filter for one month.

Participants took the Trail Making Test (TMT) to examine brain function after completing each one-month usage period with and without the HEPA filter. The TMT consists of two tasks: the first involves connecting numbers arranged on a piece of paper in the order '1→2→3→4,' measuring the ability to track visual information and the speed of hand movements; the second involves connecting numbers and letters alternately, such as '1→A→2→B,' measuring the ability to process information while switching between tasks and the ability to change one's thinking according to the situation.

When Pellegrino et al. analyzed the TMT results, they found no significant difference among all participants whether or not a HEPA filter was used. However, when they focused their analysis on participants aged 40 and over, who comprised about 42% of the group, Pellegrino et al. reported that participants completed the task of connecting numbers and letters alternately 12% faster on average after using an air purifier equipped with a HEPA filter compared to using an air purifier without a HEPA filter.

Pellegrino et al. stated that 'while a 12% improvement may not suddenly make one feel more mentally sharp, preventing cognitive decline is important for long-term health,' and argued that even a small decline in cognitive function may be associated with an increased risk of death.

While it's still unclear how air purifiers affect cognitive function, Pellegrino and his colleagues believe that 'inhaling particulate matter may affect the white matter that connects different areas of the brain.' They plan to investigate whether reducing particulate matter with HEPA filters can mitigate the impact on white matter and thus prevent cognitive decline.