Nicotine and Alcohol
Individuals who smoke and drink heavily are 38 times more likely to develop oropharyngeal (mouth-throat) cancer. By comparison, those who just drink have 6 times the risk, those who just smoke, 7 times. The risk of combined use is closer to being multiplicative than merely additive.
One clue lies in studies showing that long-term alcohol consumption increases levels of cytochrome P450, a metabolic enzyme responsible for converting the tar in cigarettes to cancer-causing chemicals.
Nicotine can also mitigate alcohol-related motor and coordination difficulties-hence the drinker who lights up to "steady his nerves."
By normalizing levels of vasopressin, a neurochemical messenger, nicotine can help counteract alcohol-induced memory impairment.
Nicotine and drugs
While the combined use of tobacco and other drugs can increase their pleasurable effects, it can also have grave health consequences.
Smokers who regularly use tobacco in combination with marijuana or crack cocaine likewise run an increased risk of cancer when compared to single-substance users. Many of the carcinogenic chemicals present in tobacco are found in marijuana, some at substantially higher levels. Individuals who smoke both drugs receive double doses of carcinogens.
On balance, though, the use of tobacco with other drugs is have a harmful effect on health, both because of the tendency to consume more of the combined substances and because of specific interactive effects like multiplied cancer risk.
Smoking is an acquired skill. By learning to inhale smoke into their lungs, individuals acquire the behaviour necessary for consuming marijuana and crack cocaine. Because underage smoking is illegal, adolescent tobacco users also learn to develop a set of masking behaviours that can serve to hide later illicit drug use.
Nicotine and caffeine
The relationship between nicotine and caffeine is complex, but researchers have shown that rats chronically exposed to caffeine self-administer nicotine at higher-than-control levels.
Compared to non-smokers, heavy smokers also prefer more heavily caffeinated beverages, such as coffee rather than tea. In addition to caffeine, other drugs shown to increase nicotine consumption in animals include pentobarbital, amphetamines, methadone, and heroin.
Finally, there is the effect of tobacco itself. Smokers have significantly lower levels of monoamine oxidase-B, the enzyme responsible for breaking down dopamine in the brain.
As a result, they are able to sustain higher levels of dopamine for longer periods of time, particularly if they continue smoking. Elevated dopamine means elevated pleasure; tobacco works synergistically with alcohol, cannabis, cocaine, and narcotics to provide a sustained high.
Hence alcohol and other drug users tend to smoke more heavily. The reverse is also true. Alcohol, a depressant, mitigates some of the adverse effects smokers' experience, such as an increased heart rate.
And alcohol activates nicotine metabolizing enzymes, which makes it necessary to consume more tobacco to achieve the accustomed effect.
Sasha Maoory - doctor and Internet writer. Visit my personal blogs http://saysmokingno.blogspot.com and http://waysquitsmoking.blogsome.com
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