Actor Robin Williams committed suicide in August after battling depression. (Tiziana Fabi/AFP/Getty Images

You'd expect the socially progressive states of the Northeast and Midwest to score well in a new state-by-state ranking of mental health services, and indeed, by some measures they do. When the advocacy group Mental Health America released the first-ever such rankings Wednesday, Massachusetts, Vermont, Maine, North Dakota, and Delaware received the highest overall scores when prevalence of mental illness is compared to access to care. Arizona, Mississippi, Nevada, Washington, and Louisiana received the lowest marks.

But read more deeply into the report, and it becomes clear that mental illness, and its treatment, defy easy categorization.

Florida, Alabama, Texas and Georgia, for example, have the lowest rates of mental illness, and nine of the 10 states with the least substance abuse are in the south. Six of the 10 states where adults report the fewest thoughts of suicide are also in that region. Because southern states always seem to score lowest on measures of physical health, I don't think I'd have guessed those outcomes.

Which is one of the points that Mental Health America, the nation's oldest mental health advocacy group, wants to make with its new report, said Paul Gionfriddo, its president and chief executive officer.

"There’s not a difference, in some respects, in what we call the 'liberal' states and the 'conservative' states," said Gionfriddo, a former state lawmaker in socially progressive Connecticut. "It doesn’t matter what the perspective is [from which] you approach creating mental health services. It matters that you put the investment into mental health services."

In that regard, disparity between states is the rule, and none are doing terribly well, he said.

"I think the main takeaway is that our country as a whole, and the states...could be doing a whole lot more on behalf of people with mental health needs," said Gionfriddo, who has written a book about the struggles of a son with schizophrenia. "When you look overall at all of the data, I don’t think there is a single state where you can say our population is healthy, and they have good access [to mental health services]."

The rankings were created by looking at 15 measures drawn from a wide variety of government surveys and some conducted for the organization. All of them are based on self-reporting. The information was compiled before Obamacare increased access to health insurance last year and probably doesn't reflect much impact from the Mental Health Parity and Addiction Equity Act of 2008, Gionfriddo said.

Overall, the report finds that 42.5 million Americans (18 percent) report some kind of mental illness -- from mild, short-term disturbances to severe, long-term illness. About 20 million (8.5 percent) say they have a problem with substance use, and 8.8 million (3.8 percent) report serious thoughts of suicide.

Among children, 6.2 million (8.5 percent) suffer from an emotional, behavioral or developmental problem; 1.6 million (6.5 percent) abuse substances and 8 percent report having attempted suicide in the past year. Girls say they have attempted suicide twice as often as boys. (Among adults, other studies show, that ratio rises to four-to-one, though men account for about 80 percent of completed suicides because they choose more lethal methods than women do.)

Getting at the cause of some of the unexpected findings is more difficult. The report states plainly that it's not clear why southerners may have fewer mental health issues, and when I pressed Gionfriddo he could offer only theories that he hopes will spark further research. Perhaps it's the weather (which can reduce the prevalence of seasonal affective disorder), the role of religion or the slower pace of life, he said.

In any event, what Gionfriddo wants is more preventive services -- early diagnosis of disorders and intervention before "Stage 4" mental health crises blow up. Even people with severe, long-term mental illnesses, such as schizophrenia, show signs early on and can be helped if providers and others move quickly, he said.

"These are not diseases that suddenly happen when someone is 20 years old and has a psychotic break," he said. "There is a wealth of information out there way before there is a crisis, way before there is a death, way before something tragic happens."