Platelet monoamine oxidase B activity changes across 31 days of smoking abstinence.

Although recent studies demonstrate that tobacco cigarette smoke substantially inhibits both central nervous system and blood platelet monoamine oxidase (MAO) activity, little is known about the time course of MAO increases after smoking cessation. Therefore, changes in platelet MAO-B activity and mood were assessed before and at multiple times after quitting smoking. Quitting smoking was associated with a significant (22%) increase in MAO activity by day 3 and with a maximum increase (about 50%) by day 10 that was maintained through day 31 of abstinence.