People who live with depression have low blood levels of a specific molecule, new medical research has revealed. It's called acetyl L carnitine, and those with particularly severe, treatment resistant or childhood onset depression were Exploring Zn(II) Acetyl l carnitine complex for simultaneous management of depression, chronic pain, and neuroprotection ScienceDirect Acetyl l carnitine deficiency in patients with major depressive disorder PNAS Frontiers Association between fatigue, peripheral serotonin, and L carnitine in hypothyroidism and in chronic fatigue syndrome