HOUSTON — People who have brain bleeds — the most lethal form of stroke — are at significantly higher risk of developing depression and dementia, according to research released Wednesday.

Previous studies of depression and stroke have focused on ischemic stroke that’s caused by blockages in blood vessels. But little is known about depression among survivors of intracerebral hemorrhage, a type of stroke that occurs when a weakened blood vessel ruptures and bleeds into the brain.

“Our study changes the way we look at depression after a hemorrhagic stroke,” said Alessandro Biffi, M.D., assistant in neurology at Massachusetts General Hospital in Boston and director of the Aging and Brain Health Research group.

“Depression is not just an isolated phenomenon following a hemorrhagic stroke. It may identify those who are likely to develop dementia, and this is important when these patients are evaluated, particularly in outpatient care settings.”

Researchers surveyed 695 survivors of intracerebral hemorrhage with no history of depression over the phone every six months for five years. They asked about mood, anxiety and cognitive performance.

During the first 50 months of follow-up after intracerebral hemorrhage, 40 percent of the study participants developed depression at a rate of about 7 percent per year — higher than the general population.

The researchers also found that factors normally associated with the risk of having another hemorrhagic stroke — lower educational levels, evidence of disease of the white matter of the brain and carrying a variant of the apolipoprotein E gene — also predicted the risk of developing depression.

Furthermore, patients who developed depression were highly likely to develop dementia later during the study. The overlap of depression and dementia was present in 63 percent of participants, and among them depression was diagnosed before the onset of dementia in 80 percent of cases, on average 18 months in advance.

“When caring for hemorrhagic stroke patients, healthcare providers tend to focus on preventing another stroke,” Biffi said. “We have found that even among patients who do not have a second stroke, the incidence of depression and subsequently dementia are very high, and healthcare providers need to be on the lookout for it to counsel patients and families.”

Researchers presented the study at the American Stroke Association’s International Stroke Conference.