From returning veterans to corporate CEOs, college students to celebrities, grandparents to children, no part of society is immune from mental illness. Some talk openly and personally about their battle. Some are very private. Some have their illness go undetected even by those closest to them.

For too long, mental illness has been shrouded in fear, misunderstanding and stigma.

Nearly one out of four Americans — 58 million people — will experience a mental illness during any given year. Mental disorders are the leading cause of disability in the United States for people between the ages of 15 and 44. In fact, the impact of mental illness on health and productivity is greater than all cancers combined.

Despite these statistics, insurance plans have long imposed limits on access to mental health services — limitations we all would find unacceptable if similarly applied to the treatment of physical illnesses.

Some of these restrictions that health plans place on mental health services include limiting the number of visits for mental health therapy, placing a dollar limit on the amount of allowable mental health treatment, requiring a higher co-payment for mental health services, and/or excluding certain diagnoses — such as post-traumatic stress disorder — and treatments from coverage altogether. Such limitations have a detrimental impact on the ability of people with mental illnesses to obtain necessary help.

I believe it is long past time for Congress to address the inequitable treatment of mental illness in our broader health care system. Mental health parity is a critical part of the solution. We must fulfill the intent of the 1996 Mental Health Parity Act and expand the definition of parity to include deductibles, co-payments, coinsurance and out-of-pocket expenses, as well as scope and duration of treatment.

However, parity alone is not a panacea to the problem of treating mental illness in this country. We must improve the range of mental health illnesses and treatment options covered by health plans, particularly for children and seniors.

Our children face enormous amounts of mental pressure from a variety of sources. Almost 21 percent of children between the ages of 9 and 17 have a diagnosable mental illness. Half of all lifetime mental illnesses begin by age 14; three quarters by age 25. Mental disorders are really the chronic diseases of the young that have a profound effect on families and society as a whole.

Children with mental illness face higher school absenteeism and dropout rates and are more likely to smoke, abuse alcohol or attempt suicide. Their grades suffer, some bully other children, and they many face disciplinary action in school. Unfortunately, only 21 percent of children in need of mental health evaluations receive them. To make matters worse, less than 20 percent of children who need mental health treatment actually receive it.

For all of these reasons, I believe all children should have the broadest health care coverage possible for mental health screening and treatment — along the lines of what is provided to children enrolled in Medicaid through the Early Periodic Screening, Diagnosis and Treatment Program. While this may not be something we can achieve for all children in the short term, it absolutely must be our long-term objective.

Medicare also has limitations on access to mental health benefits that would not be solved by mental health parity alone. For instance, commonly prescribed medications for the treatment of mental health disorders are excluded from the Medicare prescription drug program. Benzodiazepines and barbiturates are used to help seniors suffering from a variety of conditions, including anxiety, depression, insomnia, panic disorders and seizures. Some of the oldest and most effective medications aimed at treating mental health conditions are unavailable to seniors. That’s just wrong.

We know mental illness is treatable, and we can help people to live healthy, productive lives. Yet our nation’s focus on mental health has continued to take a back seat to our focus on physical health even though the two are interrelated.

Congress must act now on mental health parity and bring an end to the silent epidemic of mental illness in our country. For the sake of our children and seniors, our veterans and our loved ones, we can do no less.

Sen. Jay Rockefeller (D-W.Va.) is chairman of the Finance subcommittee on health care.