Ketogenic diet therapies in adults
Ketogenic diet therapies that are high in fat and low in carbohydrate have been used in the treatment of drug-resistant childhood epilepsy for almost a century. Approximately 40% of children show a 50% or more decrease in seizure frequency after three months following the diet, and the most common side effects are gastrointestinal (and are usually addressed with adjustments to the diet or medication). Other non-seizure benefits of ketogenic diet therapy, including increased alertness and better mood (even if seizure control is lacking), are also recognised.
Ketogenic diet therapy is believed to be similarly as effective in adults as in children, but evidence is fairly limited (perhaps partly because adults are thought to be less likely to comply). Until more research is done however, we can’t be sure that adults aren’t missing out on a viable treatment option. Scientists in London and the Netherlands, alongside three charities with expertise in ketogenic diet treatment (Matthew’s Friends, Epilepsy Society and Young Epilepsy) have recently carried out a review of ketogenic diet treatment in adults to get a better idea of its effectiveness and tolerability.
During the study 23 adults with epilepsy who were attending a specialist clinic were identified and consented. All were aged 16 or over and were either following a ketogenic diet, about to begin a ketogenic diet, or had recently stopped following a ketogenic diet. The researchers used clinical letters, seizure diaries (where available) and medical notes to find out each person’s seizure frequency before beginning the diet and three months after. Participants who showed a 50% or more reduction in seizure frequency at all follow-up points were classified as responders. The team also looked for other information about each person’s experiences that could be helpful, e.g. their diet’s effect on mood or concentration.
When they analysed their data, the scientists found that the response rate (the proportion of adults achieving a 50% or more decrease in seizure frequency whilst following a ketogenic diet) was 9/23 (39%) – very similar to that often reported in children. They also noted that the responders remained on their diets for at least a year, and were followed up for between 1 and 10 years.
Other benefits that were reported but not quantified included a reduction in seizure severity and in increase in alertness and concentration. As observed in children, these factors often encouraged subjects to continue their diet therapies, even if their seizure reduction was less than 50%. By far the most commonly reported adverse events (15/23 participants) were gastrointestinal, but these did not lead to anyone stopping the diet (seven people discontinued their diet and in six of these cases it was due to a lack of effectiveness).
These findings are helpful because they suggest that adults with epilepsy are in fact able to follow a ketogenic diet (even long term), and that diet therapies can lead to seizure reduction. The results also show that other aspects besides seizure frequency (e.g. increased concentration and alertness, decreased seizure severity) may be relevant when evaluating the success of a ketogenic diet treatment in adults. A way now needs to be found to quantify these factors and incorporate them into larger, controlled studies. If the benefits of ketogenic diet therapy are confirmed, it could become a much more widely offered treatment for adults with drug-resistant epilepsy.
Professor Sanjay Sisodiya, Professor of Neurology at University College London and Epilepsy Society, commented: ‘It is encouraging to see that the ketogenic diet might be an effective form of treatment in reducing seizures in some adults as well as children. This was a small audit and a controlled study is needed to better determine ketogenic dietary therapies response and tolerability rates in adults.’
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