Seemingly Benign Mini-Strokes May Have a Long-Term Impact on Memory
Post by Soumilee Chaudhuri
The takeaway
A transient ischemic attack (TIA), often called a "mini-stroke," is deemed to be potentially harmless as its symptoms—like slurred speech or weakness—resolve quickly. However, this recent study shows that even a single TIA can lead to long-term memory and thinking problems, similar to what happens after a full ischemic stroke.
What's the science?
A stroke happens when blood flow to the brain is blocked, causing brain damage. This can lead to lasting physical and cognitive problems. A TIA, on the other hand, often called a "mini-stroke," is characterized by temporary stroke-like symptoms caused by a brief interruption of blood flow to the brain. While its symptoms resolve quickly, prior research has hinted at potential long-term cognitive consequences. However, it’s unclear whether these cognitive changes were directly caused by the TIA event preexisting risk factors, or prior cognitive decline. Recently in JAMA Neurology, Del Bene et al., aimed to determine whether a single, diffusion-weighted image–negative TIA (a TIA without visible brain damage on imaging) was directly associated with cognitive decline over time, after accounting for vascular and demographic factors.
How did they do it?
This study analyzed data from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, which included over 30,000 participants across the United States. Researchers compared cognitive trajectories in three groups: 1) 356 people with a first-time TIA, 2) 965 people with a first-time stroke, and 3) 14,882 people with no history of stroke or TIA. Cognitive function was assessed using memory and verbal fluency tests every two years. The researchers used advanced statistical models to compare cognitive changes before and after a TIA or stroke while accounting for factors like age, race, and vascular health. Therefore, key adjustments were made for vascular and demographic risk factors, such as age, sex, race, and preexisting conditions like hypertension and diabetes. Neuroimaging (Magnetic Resonance Imaging - MRI)) was used to confirm the absence of brain damage in TIA cases (diffusion-weighted image–negative).
What did they find?
Before a stroke or TIA, people who later had a stroke already had slightly worse memory and thinking skills (cognitive composite score of -0.25) than those who had a TIA (-0.05) or no stroke at all (0). This suggests that some cognitive decline might already be happening before a stroke occurs. After a stroke or TIA, both groups showed a decline in memory and thinking skills, though the decline was faster in the stroke group. The stroke group’s cognitive composite score declined by -0.14, while the TIA group’s score changed only slightly (0.01). The control group, with no stroke or TIA, showed a small decline of -0.03. Importantly, the annual decline in cognitive function was faster in the TIA group (-0.05) compared to the control group (-0.02) and was similar to the stroke group (-0.04).
Overall, it was shown that stroke patients showed the largest immediate drop in cognitive function. TIA patients did not have an immediate decline but experienced a faster decline in cognitive function over time than the healthy control group. Surprisingly, the rate of cognitive decline in the TIA group was similar to that of stroke patients, despite the absence of visible brain damage on diffusion-weighted imaging.
What's the impact?
Even in the absence of immediate disability, TIA appears to contribute to long-term cognitive impairment, suggesting that it may trigger subtle but lasting brain changes. The result of this study raises important questions about the necessity of adding cognitive screening to the care plan for stroke and TIA patients, even if they seem to recover fully. Additionally, researchers still need to investigate how these TIA events cause memory problems so that early interventions can be used to prevent subsequent decline in brain health in these patients.