Smoking is an addictive habit where the user inhales tobacco, which contains the drug nicotine. The National Institute on Drug Abuse (NIDA) states that nicotine reaches the brain within eight seconds of smoke inhalation. Smoking can have damaging effects on the brain, resulting in addiction, brain tissue inflammation and, in severe cases, stroke.
Neurotransmitter Interaction
The NIDA states that the effects on the brain start with neurotransmitter interaction. Nicotine has a similar shape to the neurotransmitter acetylcholine; this allows nicotine to attach itself to the acetylcholine receptors in the brain. Once nicotine binds to the receptor, it sends out signals like acetylcholine would. One of the effects of nicotine mimicking acetylcholine is the release of dopamine; dopamine is another neurotransmitter, and is linked to pleasure. Nicotine increases the release of dopamine, which is why users feel pleasure from smoking. The NIDA adds that dopamine is also linked to addiction.
Neuroinflammation
ScienceDaily.com reports that another issue with smoking and the brain is neuroinflammation, or an inflammation of the brain. The cause of the inflammation is not nicotine; rather, it is a compound called NNK that is also found in tobacco. NNK is also a procarinogen, and 20 to 310ng (nanograms) are found in each cigarette. The compound increases the amounts of proinflammatory signaling proteins, proinflammatory cytokines and proinflammatory effectors in the brain. NNK also overstimulates microglial cells, causing them to attack healthy brain cells.
Stroke
In the Surgeon General's 2004 report on smoking, smoking was identified as a major cause of strokes. Strokes are the third highest cause of death in the United States. The National Institutes of Health (NIH) states that a stroke prevents blood flow to the brain, either through a blood clot or ruptured blood vessel.
