Abstracts

Rationale: Dravet syndrome (DS) is a severe, infantile-onset epilepsy syndrome commonly due to mutation of the SCN1A gene. DS patients have a high risk of sudden unexpected death in epilepsy (SUDEP). Some DS children with refractory seizures have been reported to reduce their seizures by following a strict high-fat, low-carbohydrate ketogenic diet (KD). Although the mechanisms of the KD diet is unknown, ketosis has been widely believed to contribute to the anti-epileptic effects. Here we evaluated the anticonvulsant effects of two KDs on a DS mouse model with a mutation of SCN1A (R1407X). We also tested the hypothesis that ketone bodies are necessary to reduce seizures. Methods: DS mice were randomly divided in four different diet groups to evaluate the efficacy of KD diets on seizure frequency and survival rates. The four groups were: 1) a dairy KD (F3666; Bio-Serv, Frenchtown, NJ) (n=38), 2) a non-dairy KD (TD96355; Envigo Teklad Diets, Madison, WI) (n=42), 3) dairy KD supplemented with 5% glucose in water (wt/vol) (n=52), or 4) standard mouse chow (7013; Envigo Teklad Diets, Madison, WI) (n=78). Note that, dairy KD with 5% glucose water is a high-fat diet, but it provides approximately 20% of normal daily carbohydrate levels, and is predicted to prevent ketosis. All DS mice in their home cages were monitored with video recording for 24 hours per day from postnatal day 16 (P16) to P60. Seizure frequency and mortality were compared among groups. In a separate set of experiments, DS mice (P35-P40) in each diet group (n=4-7 per group) were used to measure blood levels of β-hydroxybutyrate (β-HB), a ketone body. Results: Compared to standard mouse chow, survival rates were significantly improved in both KDs, as well as the dairy KD with glucose water. During the monitoring period (P16-P60), death occurred in 38% of DS mice with standard mouse chow (n=30 of 78). Among high-fat diet groups, only a small number of mice died (dairy KD, 8%, n=3 of 38; non-dairy KD, 5%, n=2 of 42; dairy KD with glucose water, 10%, n=5 of 52). In all mice that died, death always occurred immediately after a spontaneous generalized seizure.β-HB levels were significantly higher in mice fed both KDs compared to standard mouse chow (dairy KD vs standard, p=0.0012; non-dairy KD vs standard, p=0.0043). In contrast, mice fed the dairy KD with glucose water did not have ketosis (dairy KD vs dairy KD with glucose, p=0.0061) but there was a similar reduction in seizures and in fatality. Conclusions: Compared to DS mice on a standard diet, mice fed a dairy KD, a non-dairy KD, or a dairy KD supplemented with 5% glucose water had a significant reduction in seizures and postictal death. Previous KD studies suggest that the anti-epileptic property of KD is due to the production of ketone bodies. KDs produced high β-HB levels, but the dairy KD with 5% glucose water did not produce ketosis but still showed significant anti-epileptic effects. These results demonstrate that the elevated ketone bodies are not the main reason for the anti-epileptic effect of KDs in this mouse model of DS. Identification of the active compound(s) in KDs may allow a more targeted treatment to reduce seizures and SUDEP that may be effective in DS as well as possibly other types of epilepsy. Funding: NIH/SUDEP Center Without Walls