Mental illnesses are more common than cancer, diabetes, or heart disease. As of 2021, over 22 percent of all Americans over the age of 18 meet the criteria for having a mental illness.[34] Evidence suggests that 970 million people worldwide have a mental disorder.[35] Major depression ranks third among the top 10 leading causes of disease worldwide. By 2030, it is predicted to become the leading cause of disease worldwide.[36] Over 700 000 thousand people commit suicide every year and around 14 million attempt it.[37] A World Health Organization (WHO) report estimates the global cost of mental illness at nearly $2.5 trillion (two-thirds in indirect costs) in 2010, with a projected increase to over $6 trillion by 2030.[38]
Evidence from the WHO suggests that nearly half of the world's population is affected by mental illness with an impact on their self-esteem, relationships and ability to function in everyday life.[39] An individual's emotional health can impact their physical health. Poor mental health can lead to problems such as the inability to make adequate decisions and substance use disorders.[40]
Good mental health can improve life quality whereas poor mental health can worsen it. According to Richards, Campania, & Muse-Burke, "There is growing evidence that is showing emotional abilities are associated with pro-social behaviors such as stress management and physical health."[40] Their research also concluded that people who lack emotional expression are inclined to anti-social behaviors (e.g., substance use disorder and alcohol use disorder, physical fights, vandalism), which reflects one's mental health and suppressed emotions.[40] Adults and children who face mental illness may experience social stigma, which can exacerbate the issues