More than 26 percent of adults - one out of every four, or nearly 58 million people - suffer from a diagnosable mental disorder in a given year. For people ages 15 to 44, mental disorders are the leading cause of disability. They account for 90 percent of the roughly 30,000 suicides and 650,000 suicide attempts each year.
The toll exacted by mental disorders isn't limited to the afflicted individuals - their families and society are affected as well.
A recent estimate of the global burden of disease by the World Health Organization demonstrated that mental illnesses account for more than 15 percent of the overall burden of disease in established market economies like the United States. That's greater than the burden exacted by all cancers combined.
Make no mistake: Mental disorders are prevalent and serious. Yet health-care insurance all too often excludes or provides inadequate coverage for mental disorders.
Mental-health parity in health insurance - equating the importance of mental health to that of physical health within our health-care system and granting equal access to mental-health benefits - is vital to ensuring the best possible health outcomes for every American.
Eleven years ago, in 1996, Congress acknowledged this fundamental truth by enacting the Mental Health Parity Act.
Unfortunately, this important milestone has produced few substantive changes. For too many people, coverage for mental disorders remains subject to the whims of their employers and insurers.
A Government Accountability Office report evaluating implementation of the law revealed that employers often placed more severe coverage limits on mental-health benefits than on medical and surgical benefits.
In other words, compliance with the letter of the law has, for many people, had little impact on their access to mental-health benefits.
Recent studies have shown that having more mental-health resources available and fewer barriers to treatment results in many more people receiving mental-health treatment and a significantly lower suicide rate.
What this means - and this is important - is that tragedies like the recent shootings in Nebraska and Colorado are likely preventable if we take steps to establish parity for mental illness.
It won't be easy. Despite enactment of the Mental Health Parity Act, talking about mental illness is still largely taboo.
The issue has remained largely absent from the recent presidential health-care debates. For too many people, "mental illness" conjures images of 19th-century asylums and visions of Mrs. Rochester locked away in Jane Eyre.
And so we talk about mental health in hushed tones and whispers, preferring to hold our conversations in the shadows and behind closed doors rather than in the light of public discourse.
But the recent spate of violence has demonstrated more clearly than ever why that course is no longer an option. Unless something is done, these acts of violence will recur with a frightening regularity.
It shouldn't take a tragedy to spur Congress and policymakers to action - and we shouldn't have to ask how many more collective gasps of horror and moments of silence we must endure before Congress acts.
In the first decade of the 21st century, it's paramount that our representatives on Capitol Hill make mental-health parity an urgent national priority.
Jeffrey A. Lieberman is chairman of the Department of Psychiatry at the Columbia University College of Physicians and Surgeons.
Jeffrey A. Lieberman is chief psychiatrist at Columbia University Medical Center New York Presbyterian Hospital. E-mail him at jliebermancolumbia.edu.