City areas are hubs of hurried activities, which can provide plenty opportunities for cognitively stimulating activities, but also surge exposure to excessive noise, commonly referred to as noise pollution. Exposure to noise can lead to short term damages in cognitive function, particularly with respect to the ability to focus and remember, while some studies suggest that, similar to air pollution, chronic exposure to noise pollution may increase the risk for dementia.
Noise acts as a stress generator by bringing a state of stimulation in the body, which increases levels of stress hormones, such as cortisol. The brain is wasting resources on trying to tune out the noise, so the brain has less capacity to perform other complex tasks, leading to a temporary decline in cognitive performance.
Attention and memory tend to be the cognitive domains most impacted by noise. The stress response leads to vascular changes that can tile the way for cardiovascular disease and vascular dementia. Meta-analyses indicate that each 10 dB increase in environmental noise increases the risk for adverse cardiovascular outcomes, including hypertension and heart attacks, by 7 to 17%. Due to the strong connection between heart health and brain health, these negative effects on the cardiovascular system may account for some of the increased dementia risk from noise pollution.
Exposure to noise during the night can impair sleep quality, which has additional negative health consequences. Chronic activation of the arousal-stress response can also cause oxidative stress, which is another driver of dementia. Since moving away from an area of high noise pollution is not a practicable solution for most people, the best resolution for reducing the health dangers of noise includes practicing stress mitigation techniques, such as meditation or yoga.