A study by Nicholas Pellegrini, Doug Mrugge, and Bisha Brugga from the University of Connecticut suggests that using an in-home HEPA purifier for one month can increase brain function in adults age 40 and older. The study, which examined 119 people aged 30 to 74 living in Somerville, Massachusetts, found that participants completed a test that measured various aspects of their mental capacity, including visual memory and motor speed skills, mental flexibility, and executive function 12% faster after using the HEPA air purifier than after using a sham purifier. This improvement may seem small but crucial for preventing cognitive decline, as even small decreases in cognitive functioning may lead to a higher risk of death. However, it is unclear how these air purifiers improve cognition.