Do ketone drinks do anything for your brain or performance?

Ketone drinks raise blood ketone levels. The idea is that the brain uses ketones as an alternative fuel, which could support cognition or performance. What do the studies show so far?

For healthy, trained individuals who exercise, the results are mixed. One small study (12 trained women) showed that a ketone ester drink combined with carbohydrates improved reaction time by around 14% and attention performance by approximately 13%, but only when measured after a 10 km cycling effort. The cycling time itself did not improve. This is a promising finding, but the study is too small to draw firm conclusions from.

In people with Alzheimer's disease or mild cognitive decline, the picture is somewhat better supported. A systematic review of 10 randomised studies shows improvements in general cognition and episodic memory. There is one caveat, however: people with a genetically elevated Alzheimer's risk (via the APOE ε4 gene) respond more slowly and less strongly. Executive functions, attention and psychological wellbeing did not improve. A separate 6-month study using an MCT ketone drink in people with mild cognitive impairment also showed improvement, but all researchers involved in that paper received payments from the manufacturer. That makes the outcome less independent.

In Parkinson's disease, ketogenic therapies have so far shown no demonstrable benefit in available human studies. Animal research was more positive, but this has not yet translated into human results. In addition, a larger NIH study is under way into the effect of daily ketone drinks in older adults with elevated Alzheimer's risk, but the results are not yet available.

A small pilot study with 11 participants showed that a ketone drink can attenuate some of the cognitive effects of oxygen deprivation (e.g. at high altitude). This is purely exploratory and too early to act on.