Most Americans blame “the mental health system” – not easy access to guns or sharp political rhetoric – for the recent shootings in Tucson, Ariz.

A fairly solid 55 percent majority put “a great deal” of blame on mental health system failures and said health care professionals should be identifying people who are a danger to the community, according to the USATODAY/ Gallup Poll.

There have been published stories that the alleged shooter, Jared Loughner, could have been involuntarily committed under Arizona law.

That question aside, Americans don’t understand what a paltry amount this country spends on treatment for mental health problems. The above graphic, originally from the Substance Abuse and Mental Health Services Administration (SAMHSA), a government agency charged with monitoring substance abuse trends, shows an underwhelming 6.2 percent of health care dollars going to treat mental health issues.

That little green slice in the sea of blue looks meager enough. But in truth it’s generous, and probably includes the growing amount spent on high-priced pharmaceuticals. And it includes a lot of hard core cases that have been thrown into the Medicaid system, where institutionalization may be involved.

I’ve spoken with health care consultants who tell me that the overall percentage spent on mental health in the U.S. – minus prescription medication – stands at about 1.3 percent, and it’s been sinking rapidly over the last decade.

Part of the reason for the trend is that mental health expenditures have remained stagnant while other medical costs have increased wildly. There is less psychotherapy taking place these days as primary care physicians address depression, anxiety and other issues with a prescription pad.

Any idea of spending more on health care runs into the mantra of the day: “We just can’t afford it.”

But consider this perspective on the Tucson shooting from E. Fuller Torrey, founder of the Treatment Advocacy Center and author of The Insanity Defense: How America’s Failure to Treat the seriously Mentally Ill Endangers Its Citizens.

In a recent Wall Street Journal column, Torrey points out that the U.S. began emptying state mental hospitals in the 1960s due to civil rights concerns. The policy was enacted without a backup plan for the former patients. They were left to drift through society, homeless and untreated.

Two attacks related to Congress occurred in the 1980s. Dennis Sweeney, a man with untreated schizophrenia, shot former congressman Allard Lowenstein in 1980. Another attack by an untreated schizophrenic occurred in 1998 when two police officers were killed as the man was trying to shoot his way into the Capitol Building.

Torrey neglected to mention the most infamous example of all –John Hinckley Jr. who, in 1981, shot and seriously wounded President Reagan in a bizarre bid to impress actress Jodie Foster. He was found not guilty by reason of insanity and has been in institutional psychiatric care ever since.

“Over the past three decades, things have only gotten worse,” Torrey writes. “A 2007 study by the U.S. Justice Department found that 56% of state prisoners, 45% of federal prisoners, and 64% of local jail inmates suffer from mental illness.”

Sure, addressing these mental health issues will cost money. But it may be something we can’t afford NOT to do.

Illustration: SAMHSA via National Institute of Mental Health