How Does Smoking Affect the Brain?
The Facts
As with any addictive substance, nicotine causes certain reactions in the brain that trigger a craving for more. As of November, 2007, the addictive characteristics of nicotine accounted for 23.9 percent of male smokers, and 18.0 percent of women smokers in the United States.
Features
In spite of the tobacco industry's claim to the contrary, nicotine is a highly addictive substance which impacts the same areas of the brain as cocaine and heroin. These areas are the pleasure centers of the brain. When nicotine is ingested, a dual chemical process is at work.
It takes a mere 10 seconds from inhalation for the brain chemistry to alter. Dopamine levels (the "feel good" neurotransmitter) increase while MAO inhibitors, the enzymes that break down dopamine, are decreased.
In addition, the two enzymes responsible for converting dopamine into a useable form for brain cells to absorb are produced at higher levels. These enzymes are protein kinase A and adenylate cylase. All of these chemical reactions combined account for the immediate physicals effects of cigarette smoking.
Function
As with any chemical reaction in the brain, over time a tolerance level builds. This means that more and more of a particular substance is needed to produce the same effect. Such is the case with nicotine.
Not unlike cocaine and heroin addictions, a nicotine addiction can be just as hard to break. In addition to the physiological effects, there is a behavioral context that further supports the addiction. Often times, you'll here a former smoker say that they just don't know what to do with their hands now that they've stopped smoking. This is a prime example of a behavioral tendency that was developed along with the addiction.
Expert Insight
An article in the Journal of Neuroscience tells of a study made up of eight samples of human brain tissue from smokers and non-smokers, both deceased. The samples from former smokers were taken from subjects who had quit smoking 25 years before time of death. The study revealed high levels of both enzymes--protein kinase A and adenylate cylase--in the brain tissue of the smokers' sample.
This study concluded that the heavily induced concentrations of dopamine, protein kinase A and adenylate cylase in people who smoked for a number of years caused long-lasting changes to portions of the brain. The study went on to say that this may account for the inability of smokers to quit smoking, and for the high relapse rate among those who do try.
Risk Factors
Of significant importance is the the narrowing of blood vessels and arteries within the brain, as well as in the rest of the body, as a result of continued cigarette use. Narrowed vessels in the brain coupled with the narrow vessels leading to the brain promote a high probability for a smoker to suffer a stroke. Cigarette smoking is known to as much as double a person's risk for strokes.
Nicotine consumption may very well be a "legal" addiction, but the mechanics by which this addiction works is anything but acceptable.
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