Abstract: N-acetylaspartate (NAA) is a non-proteinogenic derivative of L-aspartic acid and represents one of the most abundant metabolites in the human brain, reaching concentrations of approximately 10 mM. It is predominantly synthesized in neurons via the mitochondrial enzyme N-acetyltransferase 8-like (NAT8L), which catalyzes the transfer of an acetyl group from acetyl-CoA to L-aspartate. Consequently, NAA biosynthesis is tightly linked to neuronal mitochondrial activity. First identified in the mid-20th century through analyses of brain tissue extracts, NAA gained scientific interest due to its unusually high concentration in the central nervous system (CNS). Its relevance increased substantially with the advent of proton magnetic resonance spectroscopy in the 1980s, which enabled NAA non-invasive in vivo detection. Owing to its neuronal specificity, NAA has since become a well-established biomarker for assessing neuronal viability and function, with reduced levels reported in various neurodegenerative and neuroinflammatory disorders, including multiple sclerosis, Alzheimer’s disease, and traumatic brain injury.