“Imagine a busy crossroad where a technical glitch in the traffic signals makes the lights go haywire. Without proper regulation, chaos descends as vehicles struggle to navigate the intersection. Similarly, when neurons misfire in certain brain regions, it can result in a surge of electrical activity, causing a seizure,” says Dr Mohd Farooq Shaikh, associate professor at Monash University Malaysia.Â
He explains that a similar type of erratic communication occurs between neurons in epileptic seizures. The root cause of these neuronal glitches is still unclear, although recent studies suggest the culprit could be in the gut.
Gut microbes leave clues
Studies have found that a complex roadway connects the brain and the gut. A network involving the central nervous system, the brain, pituitary and adrenal glands, the immune system, neurotransmitters (molecules that transmit signals) and neuromodulators (those that modulate neuron activity) work synergistically in the gut-brain axis.
It is well known that our gut contains a delicately balanced ecosystem of bacteria that help digestion. These microbes ferment the food and release metabolites or chemicals valuable to the body. One such metabolite is short-chain fatty acids (SCF), which help maintain gut wall health, ensuring no leaks.
Other bacteria produce molecules that reach the brain, cross the blood-brain barrier, and nourish brain cells called microglia. For example, a type of gut microbe, Bactereoids, produces GABA (Gamma-aminobutyric acid), which helps douse the signal excitation of neurons. However, the scale tips when the population of some types of bacteria outnumber others due to internal or external conditions. Such an imbalance directly disrupts gut wall integrity and causes leaks.
In their study, Dr Farooq and his team found that bacteria like Firmicutes, Proteobacteria, Verrucomicrobia, and Fusobacteria were more in number in the guts of people with epilepsy. In contrast, GABA-producing groups like Bacteroides were less.
Broken circuitry
In the brain, a chemical molecule called glutamate (excitatory neurotransmitter) helps the neurons to transmit the signals. At the same time, GABA acts as a switch-off for neuronal activities after the signal relay.
“When there is more excitatory neurotransmitter than an inhibitory neurotransmitter, it causes an abnormal hike in neuron firing leading to episodes of seizures,” says Dr Shaikh.
Epilepsy means a decreased level of GABA, due to which there is extra glutamate, he says.
Studies have shown that disease causing bacteria enhance the production of molecules that promote epilepsy by producing inflammation-causing molecules in the gut, ultimately undermining the ratio of inhibitory and excitatory neurotransmitters (GABA/glutamate)—all these stimulate epileptic seizures.
Read more: A holistic way to handling epilepsy
Restoring the balance
Researchers are currently exploring ways to minimise gut disruption by modifying diet, administering probiotics, or transplanting gut microbiota. These methods are found to reduce seizure occurrences significantly.
Dr Stacey K Bessone, ketogenic dietitian at Johns Hopkins All Children’s Hospital, says that a ketogenic diet is effective for those with drug resistance or GLUT1 deficiency syndrome in which the diet is the primary treatment. The keto diet is fat-rich, and the body produces energy from fats instead of carbohydrates. The reduced glucose levels in the blood and cerebrospinal fluid enhance ketones, which decrease neuron firing by stabilising the synapses.
However, Dr Bessone cautions that “the ketogenic diet for epilepsy should be monitored by a neurologist/epileptologist, a registered dietitian trained specifically on the diet and required to get the lab work for monitoring, for best result.”Â
Read more: A high fat diet can lessen epileptic seizures, finds AIIMS study
