The enzyme that makes acetylcholine from acetyl groups and choline is the choline acetyl transferase. The activity of this important enzyme has a tendency to decline during the normal aging process, causing low acetylcholine levels which in turn, are thought to contribute to the impairment of brain function that is associated with aging. † Besides maintaining normal acetylcholine levels, several studies indicate other neuroprotective benefits of acetyl-L-carnitine, which may be due to at least three modes of action. First, acetyl-L-carnitine has been shown to maintain cellular membrane stability, and to restore age-related membranal changes. † Acetyl-Lcarnitine can also act as an antioxidant, scavenging harmful superoxide radicals. Since superoxide can damage membrane lipids, this may explain acetyl-L-carnitine’s membrane protective properties. Acetyl-Lcarnitine preserves normal levels of nerve growth factor in brain tissue during aging. †