The two compounds—caffeine and EHT (Eicosancyl-5-hydroxtryptamide), a fatty acid derivative of serotonin, a neurotransmitter—combine to protect the brain against abnormal protein accumulation that's seen in Lewy body cases. Taken separately, neither compound has a protective effect on its own.
Combined, the two compounds can slow—and perhaps even stop—the progression of Lewy body dementia, say researchers from Rutgers University, who carried out tests on laboratory mice.
Coffee has already been seen to reduce the risk of Parkinson's, and researchers had assumed this was solely down to the effects of the caffeine. But coffee beans contain more than a thousand compounds, and the Rutgers researchers were particularly interested in the EHTs, which are found in the waxy coating of the coffee bean.
(Source: Proceedings of the National Academy of Sciences, 2018; 201813365)