GABRG2 and early-onset autosomal dominant Alzheimer disease: GABRG2 and GPR158 expression levels in the brain91,92 is linked to aging93,94 and adult neuropsychiatric conditions,95–97 and GPR158 expression is associated with Alzheimer disease pathology as well as frontotemporal dementia.98,99 Moreover, GPR158 downregulation is related to hippocampal-mediated cognitive deficits.93,100,101 Interestingly, glutamatergic presynaptic markers increase in MCI cortex, suggesting a paradoxical inhibitory response to dementia onset.102