Two advocacy groups accused the National Institute of Mental Health of misspending millions on what they say has been vague behavioral research. A study being released today says the government’s premier mental health agency spends little more than a third of its budget for research into severe mental illness. The agency spends more on aid studies than schizophrenia. Today’s report is being issued by groups that back research and treatment for severe forms of mental illness. They estimate that a third of all homeless people have serious mental problems but get no treatment.