Approximately 1 in 5 adults in the United States experience mental illness in a given year. Severe mental illnesses cause the brain to have trouble dealing with cognitively effortful states, like focusing attention over long periods of time, discriminating between two things that are difficult to tell apart, and responding quickly to information that is coming in fast.
source https://medicalxpress.com/news/2019-08-decodes-brain-patients-mental-illnesses.html
