Daijiworld Media Network - New York
New York, Sep 26: People who experience a transient ischemic attack (TIA), commonly known as a mini-stroke, may face a higher long-term risk of developing dementia, according to a new study published in Neurology, the medical journal of the American Academy of Neurology.
A TIA occurs when blood flow to part of the brain is temporarily blocked, causing stroke-like symptoms that usually resolve within a short period. Despite the symptoms disappearing, a TIA is considered a medical emergency because it can precede a major stroke.
Researchers analysed 20 years of healthcare data involving more than 110,000 people who had experienced their first TIA. The participants had an average age of 70, with women accounting for about half of the group. People with a previous history of stroke or dementia were excluded.
Each participant who had experienced a TIA was matched with a person from the general population who had no history of TIA or stroke. Researchers also compared around 100,000 people who had suffered a TIA with matched participants who had experienced a first stroke to examine differences in dementia risk.
During the follow-up period, 19.3% of people who had experienced a TIA were diagnosed with dementia, compared with 15.2% of those without a history of TIA or stroke.
After accounting for health and demographic factors, the researchers found that TIA was associated with a 34% higher overall risk of dementia. The risk was 75% higher during the first year following a TIA and remained elevated throughout the 20-year follow-up period.
Study author Raed Joundi, MD, DPhil, said the initial increase in dementia diagnoses could partly be linked to the greater medical attention patients receive following a TIA. However, he noted that the elevated risk did not disappear after the initial period and remained higher over the long term.
Compared with people who had suffered a stroke, those who experienced a TIA had a 33% lower risk of dementia during the first year. However, the difference narrowed over time, with the two groups developing new dementia diagnoses at similar rates after about five years.
Among people with a history of TIA, dementia occurred about three times as often as a subsequent stroke. Accounting for strokes that occurred during the follow-up period only modestly reduced the association between TIA and dementia.
The researchers cautioned that the study had limitations, including the lack of detailed brain imaging and cognitive testing. As a result, they could not determine the specific types of dementia that participants developed.
Joundi stressed that an increased risk does not mean dementia is inevitable. Most people in the study who experienced a TIA did not go on to develop dementia, he said.
The study was observational and therefore could not establish that a TIA directly causes dementia. However, the association may have implications for follow-up care after a mini-stroke, particularly in monitoring cognitive health.
Christopher Yi, a board-certified vascular surgeon at MemorialCare Orange Coast Medical Center in Fountain Valley, California, who was not involved in the research, said the findings broaden the way clinicians may need to view TIAs.
“This study suggests that we also need to think about the long-term risk of cognitive decline and dementia,” Yi said.
He cautioned that the findings do not prove that TIAs directly cause dementia and suggested that mini-strokes may instead signal underlying vascular or brain disease that contributes to both conditions.
Yi said the findings do not necessarily establish a need for formal cognitive testing for every patient, but clinicians could consider establishing a cognitive baseline and asking patients and their families about possible changes.
A TIA should not be dismissed simply because its symptoms have disappeared, he emphasised.