Bipolar disorder may often go undiagnosed and untreated in the urban poor, with 1 in 10 found to have the mental illness in a study of one New York clinic published on Tuesday.

The 13-month study at the clinic serving low-income patients found that few reported being diagnosed or treated for the illness.

Bipolar disorder is normally treated with a mood stabilizer such as lithium as well as anti-depressants to counteract the swings from dark moods to mania and associated irritability, racing thoughts, decreased need for sleep, talkativeness, and excessive involvement in risky activities.

Prescribing anti-depressants alone to bipolar patients can trigger manic behavior and rapid “cycling” between mania and Depression that could lead to suicidal thoughts, said study author Amar Das of the New York State Psychiatric Institute and Columbia University.

One earlier study estimated bipolar disorder afflicted 5.7 percent of Americans earning less than $20,000 a year, and the illness is more prevalent among the poor than other income groups, the report published in this week’s Journal of the American Medical Association said.

Of the 112 bipolar patients identified in the study, only nine said they had been diagnosed bipolar and only seven said they had taken a mood-stabilizing drug in the past month.

Since the afflicted patients were more likely to seek treatment when they were depressed, not when manic, nearly half had been diagnosed depressive. That diagnosis risked treatment solely with an anti-depressant.

“To improve the recognition and reduce the morbidity of bipolar disorders in primary care, further efforts are needed by primary care physicians to screen selectively for past hypomania or mania among participants with known Depression, anxiety, or substance use conditions,” Das wrote.