Associations Between Caffeine Consumption, Cognitive Decline, and Dementia: A Systematic Review

Area of Science:

• Neuroscience
• Epidemiology
• Nutritional Science

Background:

• Epidemiologic studies on caffeine's role in dementia and cognitive decline have yielded inconsistent results.
• Previous research has not definitively established whether caffeine consumption offers a protective effect against these conditions.

Purpose of the Study:

• To systematically review and synthesize existing literature on the association between caffeine consumption and the risk of dementia and cognitive decline.
• To evaluate caffeine's impact on cognitive performance in individuals with mild cognitive impairment (MCI) or dementia.
• To investigate how study characteristics, such as caffeine source and quantity, influence observed effects.

Main Methods:

• A systematic literature review was conducted, analyzing 61 studies published between 1990 and 2020.
• Studies were categorized based on overall outcomes (positive, negative, or no effect) and specific characteristics like caffeine source, quantity, and potential confounders.
• Outcomes related to dementia risk, cognitive decline, and cognitive function in impaired individuals were assessed.

Main Results:

• Of 57 studies on dementia risk, 28% reported positive outcomes, and 53% showed results dependent on study characteristics.
• Positive effects were more frequently observed with moderate caffeine intake (100-400 mg/day), consumption via coffee or green tea, and in women.
• Three out of four studies (75%) examining caffeine's effect on cognitively impaired individuals reported positive outcomes.

Conclusions:

• Moderate caffeine consumption, particularly from coffee or green tea and in women, may reduce dementia and cognitive decline risk.
• Caffeine may also improve cognitive function in individuals already experiencing cognitive impairment.
• Further research considering specific consumption patterns and populations is warranted.