Transient ischemic attacks linked to increased long-term dementia risk

Having a transient ischemic attack (TIA) is associated with an increased risk of developing dementia, according to a new study published September 23, 2026, in Neurology^®, the medical journal of the American Academy of Neurology. The study does not prove that a transient ischemic attack causes dementia, it only shows an association.

A TIA is when blood flow stops to a part of the brain for a short time, causing stroke-like symptoms that go away within a day with no stroke visible on brain scans. It can be a precursor to a full stroke.

"After a transient ischemic attack, there is a well-established increased risk of stroke, but less is known about the risk of dementia," said study author Raed A. Joundi, MD, DPhil, of McMaster University and the Population Health Research Institute in Hamilton, Canada. "In our study, over an average of seven years, one in five people who had a TIA developed dementia."

For the study, researchers looked at two decades of health data in Ontario to identify 113,081 people with an average age of 70 who had a first transient ischemic attack and no prior history of dementia. These participants were matched for age, sex, and health factors such as diabetes and blood pressure to people who did not have a stroke or dementia. They were also matched separately to people who had a first stroke.

Participants were followed for an average of seven years. During this time, 19% of people with TIA had a new diagnosis of dementia, compared to 15% of those without stroke or TIA and 20% of those with a stroke. Of people with TIA, there were 2.71 new cases of dementia per 100 person years and of people without TIA, there were 2.03 cases per 100 person years. Person-years represent both the number of people in the study and the amount of time each person spent in the study.

Researchers found the risk of developing dementia was highest in the first year after a TIA. After matching for age, sex, urban or rural residence, vascular risk factors like high blood pressure and diabetes, people with transient ischemic attack had a 75% increased risk of dementia in the first year compared to those without stroke. Researchers say the risk declined but remained elevated over 20 years, with an overall increased risk of 34%.

When compared to people who had a stroke, people who had a transient ischemic attack had a 33% lower risk of dementia in the first year, but after five years, the risk was similar.

People who had a TIA were three times more likely to develop dementia over the entire follow-up period than to have a stroke.

"Transient ischemic attack is associated with a large and sustained increase in dementia risk," said Joundi. "In addition, dementia occurs far more frequently after a TIA than having a stroke. This highlights that prevention strategies after a TIA should go beyond stroke prevention and consider dementia as a major long-term complication."

A limitation of the study was that researchers did not have detailed brain imaging to determine if people had hidden disease at the start of or during the study.

The analysis for this study was done at ICES, a health research institute in Ontario.