Acylcarnitines, neurocognitive disorders, and type 2 diabetes mellitus

Considerable attention has recently been focused on the carnitine pool, a complex that includes L-carnitine (LC) and acylcarnitines (ACs). Thanks to the development of omics technologies, the understanding of the multifaceted functions of the carnitine pool in the context of health and disease has become much deeper. LC, acetyl-L-carnitine (LAC), and ACs directly or indirectly affect a wide range of metabolic pathways in most organs and promote interorgan communication and metabolic interaction. Changes in ACs levels have been reported to be potentially associated with neurocognitive disorders, insulin resistance, type 2 diabetes, obesity, and cardiovascular disease. Due to its numerous properties related to neuroplasticity, LAC has the potential to become an innovative antidepressant with a unique mechanism of action. The ability of LAC to influence neuroplasticity, transmembrane modu­lation, and regulation of neurotransmitters may play a key role in the treatment of neurocognitive disorders. Researchers have proposed several mechanisms through which LC can positively impact glucose metabolism. In particular, LC promotes mitochondrial oxidation of long-chain acyl-CoA, which helps improve blood glucose control; reduces the expression of several enzymes involved in gluconeogenesis; affects the insulin-like growth factor 1 signa­ling pathway, which potentially contributes to glucose regulation; has anti-inflammatory and antioxidant properties; and also helps reduce body weight and insulin resistance. The combined effect of LC supplementation is thought to increase insulin sensitivity and improve glucose metabolism. The main purpose of this review is to analyze the importance of acylcarnitines in the prevention and treatment of comorbidities, including neurocognitive disorders and type 2 diabetes mellitus. In addition, current trends are discussed, and promising areas for future research in this area are outlined. The search was conducted in Scopus, ScienceDirect (from Elsevier), and PubMed, including MEDLINE databases. The keywords used were “acylcarnitines”, “neurocognitive disorders”, and “type 2 diabetes mellitus”. A manual search of the bibliography of publications was used to identify research results that could not be found during the online search.