In 30% of the epilepsy patients, drugs are not effective. This is termed drug resistant epilepsy. In these cases, a healthcare professional may consider to prescribe a ketogenic diet.
The dietary management of refractory epilepsy using the ketogenic diet is highly successful. Between 36% and 85% experience a seizure reduction of over 50%1, with up to 25% becoming seizure free. Although often seen in clinical practice, there is little reported in scientific literature on the cognitive benefits of the ketogenic diet in patients with refractory epilepsy. These potential additional cognitive benefits are important as 90% of parents with children suffering from epilepsy, state improved mental performance as a key goal to achieve with the ketogenic diet2. Furthermore, improvement in mental performance correlates well with adherence to the ketogenic diet2.
The Epilepsy Behavior journal publishes ‘Cognitive benefits of the ketogenic diet in patients with epilepsy: a systematic overview ’.
This systematic overview of clinical studies reports on the mental performance in adults and children with epilepsy on ketogenic diet.
Papers included
The search of the clinical literature uncovered 33 papers discussing cognitive changes with the ketogenic diet. Most of the papers concerned either retrospective or prospective studies; only one randomized clinical trial was found.
A substantial number of studies used subjective measurements of cognitive performance, meaning these papers assessed the experience of the patient in general, without using standardized methods. Ten papers used objective measurements making use of cognitive or neuropsychological tests, which are more standardized and often statistically tested.
Conclusions
The main conclusion of the literature analysis is that the subjective cognitive improvements are frequently observed in patients with epilepsy on the ketogenic diet. Cognitive improvements primarily include alertness, attention, concentration and global cognition. Objective tests confirmed the improvements in alertness, but not in global cognition, such as IQ.
The cognitive benefits may be achieved by a combination of direct effects of the ketogenic diet on cognition and through seizure reduction. The improvements were seen across a wide range of epileptic syndromes, including GLUT1 syndrome, infantile spasms, Dravet syndrome, Continuous
Slow Waves during Sleep (CSWS), Tuberous Sclerosis Complex (TSC), pyruvate dehydrogenase complex deficiency (PDCD) and Myoclonic Status in Non-Progressive encephalopathy (MSNPE). Both infants, children, as well as adults across different age categories, experienced improvements in cognition. These effects were seen in patients on the classic ketogenic diet and in patients using the Modified Atkins Diet.
Additionally, no indication was found that the improvement in cognition on a ketogenic diet in patients with epilepsy is influenced by antiepileptic drugs (AED) reduction. The effects were found in patients who reduced their medicine intake, as well as in those who remained on anti-epileptic drugs during the dietary intervention.
Future research
Additional research is needed to confirm findings. Specifically, more randomized clinical trials are needed that include a wide range of objective measurements and appropriate controls. Such studies would help to understand whether the observed cognitive effects are intrinsic to the ketogenic diet or an indirect consequence of other improvements (e.g. through the action of seizure reduction). Authors feel given the motivational aspect of the positive impact of the ketogenic diet on cognition, the results of reviewed and future studies should be communicated to patients with epilepsy and their caregivers.