Autism and Epilepsy: Synaptic Dysfunction Plays a Role in Both Entities

Abstract

Autism is associated with synaptic dysfunctions, leading to disturbances in neural circuit connectivity. The result is an impaired synaptic pruning process, which removes extra connections, causing an overabundance of the synaptic system in autistic brains. Mutations in genes associated with synapse formation, elimination, transmission, and plasticity also contribute to this dysfunction, potentially changing social communication and behavior. During brain development, healthy brains undergo synaptic pruning, where unnecessary connections are eliminated. Especially in autism spectrum disorders, this process is often less effective, leading to a change of number of synapses. This higher number of synapses can disrupt normal communication pathways, contributing to autistic symptoms. Different genes associated with an increased risk for autism also play important roles in synaptic maturation and function. Mutations in these genes can lead to defects in synapse formation, maintenance, and communication. Many different proteins are essential for synapse function, such as those encoded by genes like SHANK3, are often affected in autism spectrum disorders. Defects in these proteins can alter synaptic structure and signaling, impacting synaptic plasticity. The combination of increased synapse numbers and impaired synaptic function can result in disturbed neural circuit connectivity. This disrupted connectivity affects how the brain processes information and relates to the core symptoms of autism, including difficulties with social communication and repetitive behavioral symptoms. Synaptic dysfunction plays an important role in the co-occurrence of autism spectrum disorders and epilepsy forms, as it underlies the common neurobiological features shared by both conditions. Disrupted synaptic function, which involves the communication between neurons, leads to an imbalance between excitatory and inhibitory signals in the brain, increasing the risk for both ASD-related challenges and epileptic seizures. This dysfunction can stem from genetic mutations affecting synaptic proteins or other cellular processes, leading to both developmental delays, autism-like behaviors, and increased susceptibility to seizures. Further research has to focus on the biochemical mechanism of synaptic function and dysfunction in both entities in childhood.