Mental health care is one of the biggest unmet needs of our time. Nearly one in two people in the U.S. will suffer from depression, anxiety disorders or another mental health ailment at some point in their life, and about one in 17 Americans currently has a serious mental illness. Young people are especially prone to these troubles. Yet millions of people living with these conditions do not receive the care they require. In recent years the health system and state and federal governments have taken steps to right that wrong. Progress has been slow, and budget cuts and legal wrangling have now put many of these measures at risk. Doctors, insurers and politicians need to pick up the pace.

Mental illness strikes without regard for economic class, but the strain is acute for people with low incomes. About one in six adults living at just above the poverty line or lower has severe mental health problems. Without access to affordable treatment, many have a hard time holding down a job yet do not qualify as formally disabled, thus leaving them locked out from insurance coverage. A recent large study in California found that only 32 percent of uninsured residents with mental illnesses received any treatment at all and that less than 12 percent got adequate help.

The human and economic toll is enormous yet often hidden. Untreated mental illnesses in the U.S. cost more than $100 billion a year in lost productivity, according to the National Alliance on Mental Illness (NAMI). Local hospitals and clinics must cope with associated chronic physical diseases. Schools have to open more special education classes. Courts and jails handle a large number of individuals who suffer from untreated mental illnesses. Suicide ranks among the top 15 most common killers in the U.S. (in the top three among young people), and 90 percent of cases can be attributed to mental illness.

The severity of the problem has prodded politicians into action. By 2002, 29 states had mandated that health insurance packages cover mental illness on the same terms as physical illness, and in those states the suicide rate fell by an average of 5 percent. But equalizing coverage means little to those who lack insurance altogether, and states are increasingly failing to make provision for them. In the past three years states have cut up to 39 percent of their mental health budgets, according to NAMI.

The Patient Protection and Affordable Care Act, which President Barack Obama signed into law in 2010, should help fill these holes. It requires that insurance plans offer “behavioral health” coverage, including mental health and addiction and substance abuse help, as an “essential health benefit.” At least 3.7 million Americans who are currently living with severe mental illness will get new benefits for their conditions by 2014, either through extended Medicaid coverage or insurance exchanges.

Yet these measures are in legal jeopardy. The U.S. Supreme Court will hear arguments for and against the constitutionality of the act late in March. If the court rules that states do not have to expand their Medicaid programs, as the act currently requires, it could shut out 16 million Americans who would otherwise receive Medicaid coverage for mental health. A ruling that closes the state insurance exchanges would deprive another 16 million. Scuttling the law would also do away with plans to build national centers for the treatment of depression and to improve the way behavioral health services are integrated into standard care.

If the law falls, Congress must reinstitute its most crucial provisions, and even if it stands we all have more to do. Insurance alone does not guarantee that people get the care they need; doctors and social workers must work to ensure that. Drug companies must refill the research pipeline for new drugs, which has been sorely neglected [see “Lifting the Black Cloud,” by Robin Marantz Henig, on page 66], and develop other treatments. And all of us should get over the stigma we still tend to attach to these conditions. The rewards will be that millions of our friends, neighbors and children will have a chance to become healthier, happier and more productive members of society.

This article was published in print as "A Neglect of Mental Illness."