The figure rose to almost 30% of those in the 18 to 25 age group, compared with 14.3% of patients 50 and older, according to researchers from the Substance Abuse and Mental Health Services Administration (SAMHSA).
And of the nearly 46 million U.S. adults who reported having had a mental, behavioral, or emotional disorder when surveyed in 2010, some 60% didn't receive any treatment for the condition.
The most common reason for not getting mental healthcare was not being able to afford it.
The researchers noted that although the 20% figure is "relatively high," just 5% reported having serious issues that interfered with their normal activities.
Although more of those with serious mental illness reported receiving treatment, a large proportion -- 39% -- didn't receive any mental health services.
The unemployed, Medicaid beneficiaries, and those living below the poverty level were more likely to have mental illness in the preceding year, as were younger patients. Women appeared to be at greater risk than men (23% versus 16.8%).
Substance use disorders were more common among those with mental illness than among those reporting no disorders (20% versus 6.1%), and the prevalence was even higher among patients with serious mental illness (25.2%).
The findings emphasize the need for mental health treatment specialists to address substance use disorders, and to more extensively integrate mental health and substance use treatment centers, the researchers wrote.
They also reported that many Americans had seriously contemplated suicide over the preceding year (8.7 million), and 2.5 million had actually made suicide plans. Just over a million patients had attempted it.
Signs of mental illness were also seen in American youth, with 8% of 12-to-17-year-olds reporting a major depressive episode -- being in a depressed mood for at least two weeks -- in the preceding year.
Children and adolescents who reported feeling this way were more likely to use drugs than those who didn't have a depressive episode (37.2% versus 17.8%), they found.
The researchers called for screening kids who've had a major depressive episode for substance use disorders.
The data come from SAMHSA's National Survey on Drug Use and Health 2010.
In a statement, SAMHSA administrator Pamela Hyde warned that mental illness is often concurrent with cardiovascular disease, diabetes, and obesity, and that "treatment of the mental illness can reduce the effects of these disorders
http://www.medpagetoday.com/Psychiatry/GeneralPsychiatry/30776
