Scientists have reported on the risk of dementia after a transient ischemic attack

People who have had a transient ischemic attack (TIA) are more likely to experience dementia in subsequent years. This conclusion was reached by researchers who studied the medical data of more than 113 thousand residents of the Canadian province of Ontario. The association was most noticeable in the first year of follow-up, but the increased risk persisted in the future. How scientists obtained these results and why short—term symptoms should not be ignored is described in the "Izvestia" article.

What is a transient ischemic attack?

With a transient ischemic attack, the blood supply to a part of the brain is temporarily disrupted. A person's arm or leg may suddenly weaken, speech may change, vision may deteriorate, or other symptoms similar to signs of a stroke may appear. Then they pass, sometimes in a few minutes. However, the disappearance of symptoms does not mean that the danger is over.: A TIA may precede a stroke and requires an urgent medical assessment.

The association of TIA with subsequent stroke is well known. The group of McMaster University neurologist Raed Jundy decided to study in more detail another possible consequence — dementia.

How the study was conducted

The researchers analyzed the medical data of Ontario residents for the years 2002-2022. They identified 113,081 people who had TIA for the first time. The average age of the participants was 70 years old, and they had not been diagnosed with dementia before the attack.

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For comparison, the researchers selected people without stroke and TIA, who were comparable in age, gender, and a number of vascular-related factors. Separately, the results were compared with the data of patients who had suffered a stroke for the first time. Follow-up began 90 days after the attack; people with previously diagnosed dementia or stroke, as well as those who died in the early period, were excluded from the analysis. On average, the participants were followed for just over seven years.

During this time, dementia was diagnosed in about 19% of people after TIA. In the group without TIA and stroke, the rate was 15%, and among stroke survivors — 20%. Taking into account the duration of follow-up after TIA, 2.71 new cases of dementia per 100 person-years were recorded against 2.03 cases in the comparison group. The man-years allow us to take into account both the number of participants and the time during which each of them was monitored.

When was the risk the highest

The researchers found the most pronounced difference in the first year of follow-up: after taking into account age, gender, place of residence and vascular factors, the risk of dementia diagnosis in people after TIA was 75% higher than in the group without stroke. Then the difference decreased, but remained for a long period of observation. Overall, the relative risk was 34% higher.

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These percentages describe the difference between groups, not the likelihood that a particular person will develop dementia. In the study, about one in five participants received a diagnosis after TIA; most did not experience it during the follow-up period.

In the first year, the risk of dementia after a TIA was lower than after a stroke. Five years later, the indicators in these groups became comparable. At the same time, in the group of TIA patients, new diagnoses of dementia occurred about three times more often during follow-up than subsequent strokes. The authors believe that when assessing the long-term effects of TIA, attention should also be paid to cognitive health.

Does this mean that TIA causes dementia?

The study found a link, but did not prove that it is a transient ischemic attack that causes dementia. Medical records were used for the analysis, but scientists did not have detailed brain scans that would help assess possible hidden changes before the attack and during observation. Also, this work did not check which measures after TIA can reduce the risk of dementia.

The practical conclusion concerns primarily the reaction to the attack itself. If weakness suddenly appears on one side of the body, speech or vision is impaired, emergency medical care is needed, even when the symptoms have passed quickly. Doctors should determine the cause of the incident and assess the risk of stroke. A new study shows why it is important to consider a person's condition after TIA in the long term.