This study investigates the relationship between green tea consumption and the development of cerebral white matter lesions (WML) in older people without dementia. In a large-scale Japanese cohort study with 8,766 participants, the brain structure was recorded using MRI scans and the consumption of green tea, black tea and coffee was documented using a questionnaire.
The results show that a higher consumption of green tea was associated with a lower volume of white matter lesions. This persisted even after adjustment for confounding factors such as age, gender, education, hypertension and lifestyle. No significant associations were found for the consumption of coffee or black tea.
Conclusion: Regular green tea consumption could play a preventive role in reducing cerebral white matter lesions, which are associated with an increased risk of dementia and cognitive impairment. Further long-term studies are needed to further investigate this relationship.
Background:
Ageing is a major risk factor for neurodegenerative diseases such as dementia. Structural brain changes, in particular the increase in white matter lesions (WML), are closely linked to cognitive decline. Green tea contains bioactive compounds such as epigallocatechin gallate (EGCG), which have antioxidant and anti-inflammatory properties and may have neuroprotective effects. Previous epidemiological studies suggest that tea and coffee consumption may be associated with better cognitive function in old age.
Aims of the study:
This study investigates the influence of green tea, black tea and coffee on brain structure, in particular white matter lesions, hippocampal volume and total brain volume in older adults without dementia.
Methodology:
– Participants: 8,766 people from the Japan Prospective Studies Collaboration for Aging and Dementia (JPSC-AD).
– Survey:
– Food intake by means of a Food Frequency Questionnaire (FFQ).
– Brain scans using magnetic resonance imaging (MRI).
– Analyzes:
– Multivariate statistical models to investigate the associations between beverage consumption and brain structure.
– Consideration of confounding factors such as age, gender, high blood pressure, BMI, blood lipids and lifestyle factors.
Results:
1. Green tea and white matter lesions:
– People with a daily consumption of ≥600 ml of green tea had significantly less WML than people who drank less than 200 ml per day.
– The trend also remained after adjustment for other influencing factors(p-value for the trend = 0.007).
– The reduction in WML was particularly pronounced in people without depression and without the ApoE-ε4 gene, which is associated with a higher risk of Alzheimer’s disease.
2. No significant correlation with hippocampus or total brain volume:
– While WML were reduced, there were no significant differences in hippocampal volume or total brain volume between different tea consumption groups.
3. No effect from coffee or black tea:
– Coffee showed no significant correlations with WML, hippocampus or total brain volume.
– Black tea was not analyzed further due to the small number of consumers.
Discussion:
– The reduction of white matter lesions by green tea could be mediated by several mechanisms:
– Blood pressure-lowering effects: Green tea can lower systolic and diastolic blood pressure, which has a positive effect on cerebral blood flow.
– Antioxidant effect: Catechins in green tea can reduce oxidative stress, which plays an important role in neurodegeneration.
– Anti-inflammatory properties: Green tea inhibits pro-inflammatory signaling pathways such as NF-κB and can thus reduce micro-inflammation in the brain.
– The study suggests that green tea could play a role particularly in the early stages of neurodegenerative processes.
Restrictions:
– The study is observational and therefore cannot prove any causal relationships.
– There is a lack of detailed information on the type of tea preparation that could influence the catechin content.
– The results are based on a Japanese population, which is why the transferability to other ethnic groups needs to be investigated further.
Conclusion:
Higher consumption of green tea is associated with a reduction in cerebral white matter lesions, suggesting a potential protective effect against vascular and neurodegenerative diseases. Further long-term studies are needed to clarify the causal relationship and possible mechanisms.