Chunk #12 — 3. Results — 3.2 Association of Suicide with Current Smoking — 3.2.1. Possible Mechanisms — 3.2.1.2. Smoking as a Psychological or Physical Toxin
Another possible mechanism is that low levels of monoamine oxidases (MAOs) A and B--enzymes that metabolize noradrenaline--are often, but not always, associated with suicide (Van Kempen et al. 1992). Current smokers have lower levels of MAOs than never-smokers (Fowler et al. 2003; Lewitzka et al. 2008). Importantly, former smokers do not have lower levels suggesting active smoking is what is causing the low MAO levels (Fowler et al. 2003). Also importantly, nicotine itself is not the cause of the lower MAO levels (Fowler et al. 2003); rather harmon alkaloids appear to be the cause (Herraiz & Chaparro 2005).
