Methyl donation is a process in which a molecule donates a methyl group (-CH3) to another molecule. Methyl groups play important roles in biological processes, including DNA methylation, protein methylation, and neurotransmitter synthesis. Methylation is a process by which a methyl group is added to a molecule, often altering its function or activity.

In the brain, methyl donation is important for the synthesis of neurotransmitters such as dopamine, epinephrine, and norepinephrine. These neurotransmitters play key roles in regulating mood, attention, and alertness. Methyl groups are also involved in the synthesis of phosphatidylcholine, a major component of cell membranes in the brain.

Methyl donation is mediated by enzymes called methyltransferases, which transfer methyl groups from donor molecules such as S-adenosylmethionine (SAM) to acceptor molecules. SAM is a methyl donor molecule that is synthesized from the amino acid methionine. SAM donates its methyl group to other molecules through a process called transmethylation.

Methyl donation is a tightly regulated process that can be affected by a variety of factors, including diet, stress, and environmental toxins. Disruptions in methyl donation have been linked to a number of neurological and psychiatric disorders, including depression, anxiety, and schizophrenia. For example, abnormalities in DNA methylation have been observed in individuals with these disorders, suggesting a role for disrupted methyl donation in their pathophysiology.