Gulf Coast resident and researcher’s predictions have been confirmed after the first study to rigorously assess the mental health fallout from Hurricane Katrina. Mood problems after the storm occurred about as often as in any natural disaster ever studied, and that the delayed government response almost certainly made the problem worse.

The analysis, a continuing survey of more than 1,000 residents of New Orleans and surrounding areas, found that 17 percent of people in the city reported signs of serious mental illness in the month after the disaster, compared with 10 percent in surrounding areas. The estimated prevalence of such problems in the general population is 1 to 3 percent in any month.

Post-traumatic stress symptoms, which include flashbacks, nightmares, a hair-trigger temper, were by far the most common type of mental problem and were often associated with incidents that happened in the storm’s wake, like property losses, robberies and assaults.

Nearly half of New Orleans residents in the survey reported some significant symptoms of anxiety in that first month after the storm, about as high as can be expected in a community hit by a natural disaster, according to the study, being published today in the Archives of General Psychiatry. Women, young adults and lower-income residents were hardest hit, just as studies of previous disasters have found.