If you get dizzy several minutes after standing up you may be at risk of a serious medical condition, new research from Harvard Medical School indicates. That condition is delayed orthostatic hypotension.

Orthostasis means upright posture, while hypotension means low blood pressure. Taken together, orthostatic hypotension is a drop in blood pressure within three minutes of standing or sitting, according to Dr. Christopher Gibbons, study author and a fellow with the American Academy of Neurology. The symptoms of this condition include dizziness, faintness, or lightheadedness.

Over 20 years ago, researchers introduced the concept of delayed orthostatic hypotension — a fall in blood pressure on standing that occurs after the crucial three-minute cutoff point. Past research suggests this delayed condition occurs as frequently as orthostatic hypotension, while today doctors recognize it as an early and milder form of the root condition. However, though it's clear the delayed version can progress over time, how often does that happen?

To find out, Gibbons and his co-researchers reviewed the medical records of 165 people who completed nervous system testing at an average age of 59. Of the total patients, 48 received a diagnosis of delayed orthostatic hypotension, 42 had orthostatic hypotension, and 75 did not have either condition. For 10 years after this initial exam, all of the patients, no matter their condition, were followed.

Over 10 years, 54 percent of the patients diagnosed with delayed orthostatic hypotension progressed to orthostatic hypotension, the researchers found, while 31 percent developed a degenerative brain disease, including Parkinson's and dementia.

The death rate (during the decade-long surveillance period) for people with delayed orthostatic hypotension was 29 percent, for those with orthostatic hypotension 64 percent, and for people without either condition 9 percent. Fully half of those whose delayed condition progressed to orthostatic hypotension died.

The researchers also discovered people with delayed orthostatic hypotension and diabetes were more likely to progress to the full condition than those without diabetes. Importantly, many of the people who began the study with the delayed condition but did not progress were taking medications that may have affected their blood pressure, such as diuretics and antidepressants.

“These data suggest that delayed orthostatic hypotension is an earlier, milder form of orthostatic hypotension that, with time, will progress to orthostatic hypotension in more than half of the patients and carries a similar poor prognosis,” wrote the authors. That said, earlier diagnosis and proper medication may be able to add years to many such lives.

Source: Gibbons CH, Freeman R. Clinical implications of delayed orthostatic hypotension: A 10-year follow-up study. Neurology. 2015.