Study shows association between higher fish intake and lower risk of stroke, dementia in healthy people
Consuming a diet rich in fish had the greatest protective effect on people younger than 75 years old, reveals a recent study.
France: Results from a large population-based study suggest that intake of two or more servings of fish a week is associated with a lower cerebrovascular disease (CVD), especially in people younger than 75 years. This implies their beneficial effect on brain vascular health before the manifestation of overt brain disease. The study findings were published in Neurology, the medical journal of the American Academy of Neurology.
"Our results are exciting because they show something as simple as eating two or more servings of fish each week is associated with fewer brain lesions and other markers of vascular brain damage, long before obvious signs of dementia appear," said study author Cecilia Samieri, PhD, of the University of Bordeaux in France. "However, eating that much fish did not have a protective effect in people 75 years of age and older."
The study does not prove that eating fish prevents dementia, it only shows an association between the two.
Fish intake is known to prevent CVD but the mechanisms behind it are not clear, especially regarding its impact on subclinical damage. Assuming that fish may have a pleiotropic effect on cerebrovascular health, Samieri and the team investigated the association of fish intake with global CVD burden based on brain MRI markers.
The cross-sectional analysis included participants from the Three-City Dijon population-based cohort (aged ≥65 years) without dementia, stroke, or history of hospitalized cardiovascular disease who underwent brain MRI with an automated assessment of white matter hyperintensities, visual detection of covert infarcts, and grading of dilated perivascular spaces.
Using a frequency questionnaire, fish intake was assessed and the primary outcome measure was defined as the first component of a factor analysis of mixed data applied to MRI markers.
Fish intake was assessed through a frequency questionnaire and the primary outcome measure was defined as the first component of a factor analysis of mixed data applied to MRI markers. The association of fish intake with the CVD burden indicator was studied using linear regressions.
A total of1,623 participants (mean age, 72.3 years; 63% women) were included in the study.
The study revealed the following findings:
- The first component of factor analysis (32.4% of explained variance) was associated with higher levels of all three MRI markers. Higher fish intake was associated with lower CVD burden.
- In a model adjusted for total intracranial volume, compared to participants consuming fish <1 per week, those consuming fish 2-3 and ≥4 times per week had a β = -0.19 and β = -0.30 lower indicator of CVD burden, respectively.
- We found evidence of effect modification by age, so that the association of fish to CVD was stronger in younger participants (65-69 years) and not significant in participants aged ≥75 years.
- For comparison, in the younger age group, consuming fish 2-3 times a week was roughly equivalent (in opposite direction) to the effect of hypertension.
"In individuals without stroke or dementia, higher fish intake is associated with lower subclinical CVD at MRI," wrote the authors.
"Our findings showed that a higher frequency of fish intake was associated with lower CVD burden, especially among participants younger than 75 years, suggesting a beneficial effect on brain vascular health before the manifestation of overt brain disease," they concluded.
"More research is needed to help us understand the mechanism of how eating fish may preserve brain vascular health, because diet is a factor people can modify to possibly decrease their risk of cognitive decline and even dementia later in life," Samieri said.
Fish Intake and MRI Burden of Cerebrovascular Disease in Older Adults. Aline Thomas, Fabrice Crivello, Bernard Mazoyer, Stephanie Debette, Christophe Tzourio, Cecilia Samieri. Neurology Nov 2021, 10.1212/WNL.0000000000012916; DOI: 10.1212/WNL.0000000000012916