Persistent Effects of the Ketogenic Diet on the Core Symptoms of Autism in BTBR Mice

ABSTRACT BACKGROUND: The Ketogenic Diet (KD), is a high fat, low carbohydrate dietary regimen, that has been shown to treat a diverse array of medical conditions, most notably the seizure associated with epilepsy. Recent studies have demonstrated that in addition to reducing seizure frequency, the KD has antiepileptogenic effects that continue after reversal to control diet (CD). Such results indicate that the KD does not only suppress seizures in adult mice and rats, but it is potentially effective in attenuating long-term disease progression. Furthermore, studies on autism spectrum disorder (ASD) in a murine mouse model (BTBR mice) found that KD treatment improved autistic behaviors by increasing sociability in a three-chamber test and decreasing self-directed repetitive behavior. This study will use the BTBR mouse model to determine if improvement in ASD-associated behaviors persists when animals are returned to a CD. METHODS: BTBR mice at 5 weeks of age were randomly assigned to one of three diet groups: CD, KD, and KD reversal. All mice underwent three-chamber behavioral testing (a test of sociability and self-directed repetitive behaviors in autistic models of mice) followed by two periods lasting three weeks. During the first period, both KD group and KD reversal groups were switched to KD for three weeks and underwent three-chamber behavioral testing. Subsequently, both groups underwent three additional weeks of KD, however in the last 5 days of the second period the reversal group was reverted to the CD and underwent their final three-chamber behavioral test. Body weights and blood chemistry (glucose and ketone levels) of each mouse was measured before treatment (five weeks of age; Test 1) as well as after three weeks of diet administration (eight weeks of age; Test 2) and after 6 weeks of diet administration (eleven weeks of age; Test 3). RESULTS: Although it was expected that enhanced sociability would be observed and continue after reversal to the CD, no significant improvements in sociability (characterized by ratio of phase 2, preference for sociability phase, compared to phase 1, the non-social phase) were found in any treatment group. Blood analysis revealed the hallmark characteristics of KD treatment, including weight loss, decreased glucose, and increased β –hydroxybutyrate levels were found in the KD and KD reversal group in Test 2. Additionally, weight glucose, β –hydroxybutyrate levels returned to baseline levels after 5-day reversal to CD. CONCLUSION: Despite detected metabolic changes induced by the KD, no notable improvements in sociability were detected when the entire sample size was analyzed. These data conflict with previous research thus ongoing research will consider methodological differences and include additional measures of sociability including frontal contact and self-directed repetitive behaviors