Valproate use associated with frontal and cerebellar gray matter volume reductions: A voxel-based morphometry study

Sodium valproate is associated with cortical thinning of disease-specific areas in juvenile myoclonic epilepsy

BACKGROUND

Juvenile myoclonic epilepsy (JME) is associated with cortical thinning of the motor areas. The relative contribution of antiseizure medication to cortical thickness is unknown. We aimed to investigate how valproate influences the cortical morphology of JME.

METHODS

In this cross-sectional study, individuals with JME with and without valproate, with temporal lobe epilepsy (TLE) with valproate and controls were selected through propensity score matching. Participants underwent T1-weighted brain imaging and vertex-wise calculation of cortical thickness.

RESULTS

We matched 36 individuals with JME on valproate with 36 individuals with JME without valproate, 36 controls and 19 individuals with TLE on valproate. JME on valproate showed thinning of the precentral gyri (left and right, p<0.001) compared with controls and thinning of the left precentral gyrus when compared with JME not on valproate (p<0.01) or to TLE on valproate (p<0.001). Valproate dose correlated negatively with the thickness of the precentral gyri, postcentral gyri and superior frontal gyrus in JME (left and right p<0.0001), but not in TLE.

CONCLUSIONS

Valproate was associated with JME-specific and dose-dependent thinning of the cortical motor regions. This suggests that valproate is a key modulator of cortical morphology in JME, an effect that may underlie its high efficacy in this syndrome.

Understanding the role of AMPA receptors in autism: insights from circuit and synapse dysfunction

Autism spectrum disorders represent a diverse etiological spectrum that converge on a syndrome characterized by discrepant deficits in developmental domains often highlighted by concerns in socialization, sensory integration, and autonomic functioning. Importantly, the incidence and prevalence of autism spectrum disorders have seen sharp increases since the syndrome was first described in the 1940s. The wide etiological spectrum and rising number of individuals being diagnosed with the condition lend urgency to capturing a more nuanced understanding of the pathogenic mechanisms underlying the autism spectrum disorders. The current review seeks to understand how the disruption of AMPA receptor (AMPAr)-mediated neurotransmission in the cerebro-cerebellar circuit, particularly in genetic autism related to SHANK3 or SYNGAP1 protein dysfunction function and autism associated with in utero exposure to the anti-seizure medications valproic acid and topiramate, may contribute to the disease presentation. Initially, a discussion contextualizing AMPAr signaling in the cerebro-cerebellar circuitry and microstructural circuit considerations is offered. Subsequently, a detailed review of the literature implicating mutations or deletions of SHANK3 and SYNGAP1 in disrupted AMPAr signaling reveals how bidirectional pathogenic modulation of this key circuit may contribute to autism. Finally, how pharmacological exposure may interact with this pathway, via increased risk of autism diagnosis with valproic acid and topiramate exposure and potential treatment of autism using AMPAr modulator perampanel, is discussed. Through the lens of the review, we will offer speculation on how neuromodulation may be used as a rational adjunct to therapy. Together, the present review seeks to synthesize the disparate considerations of circuit understanding, genetic etiology, and pharmacological modulation to understand the mechanistic interaction of this important and complex disorder.