Study: 2–3 Cups of Coffee a Day Linked to Lower Dementia Risk

A long-running study of U.S. adults finds that drinking caffeinated coffee regularly is associated with a substantially lower risk of dementia and better cognitive health with age. Dementia is a general term for conditions that progressively impair memory, thinking and everyday functioning, with Alzheimer's disease the most common cause. Participants were followed for up to 43 years, giving researchers a long view of how daily habits relate to brain health.

Dementia rates

Among people who drank higher amounts of caffeinated coffee, researchers recorded 141 dementia cases per 100,000 people each year. For those who rarely or never drank it, the rate was 330 cases per 100,000 per year.

Higher coffee drinkers were also less likely to report subjective cognitive decline, meaning memory or thinking changes people notice themselves that have not been confirmed by formal testing. This was reported by 7.8% of the higher-consumption group, compared with 9.5% of those who rarely or never drank caffeinated coffee.

How much is best

The strongest associations appeared among people who drank two to three cups of caffeinated coffee a day. The link held regardless of participants' genetic risk of dementia. Drinking more than that range did not appear to add protection.

Tea and decaf

Tea was also linked to lower dementia risk and better cognitive function, with the most favorable results at one to two cups daily. The study did not separate caffeinated from noncaffeinated tea, so it cannot show whether caffeine explains the tea findings. Decaffeinated coffee did not show the same benefits, which suggests caffeine may play a role, though this does not establish it as the cause.

Limitations

The results show an association, not proof that coffee prevents dementia. Other differences between coffee drinkers and people who avoid it could contribute to the findings. Further research is needed to determine whether these drinks directly influence dementia risk.