Glucometabolic Changes Are Associated with Structural Gray Matter Alterations in Prodromal Dementia

Background: Glucometabolic changes, such as high glycemic load (GL) diet and insulin resistance (IR), are potential risk factor of Alzheimer's disease (AD). Yet, the effect of these factors on brain alterations that contribute to AD pathology has not been clearly demonstrated. Objective: We aimed to assess the relationship of GL and IR with gray matter volumes involved in prodromal dementia. Methods: GL and Triglyceride-Glucose (TyG) index, an IR surrogate marker, were calculated in 497 participants who underwent magnetic resonance imaging (MRI). The gray matter volumes most related to prodromal dementia/mild cognitive impairment (diagnosed in 18/158 participants during the 7-year follow-up) were identified using a data-driven machine learning algorithm. Results: Higher GL diet was associated with reduced amygdala volume. The TyG index was negatively associated with the hippocampus, amygdala, and putamen volumes. Conclusion: These results suggest that GL and IR are associated with lower gray matter volumes in brain regions involved in AD pathology.