Nicotine is a stimulant drug found in cigarettes, cigars, pipe tobacco, and smokeless tobacco. Nicotine is highly addictive; in fact, it is as addictive as heroin and cocaine. Nicotine reaches the brain within 8 seconds of inhalation. Its effects on the body include increased heart rate and blood pressure, increased alertness, and reduced appetite.
Although nicotine is an addictive substance, it is actually the tobacco in nicotine products that can cause deadly cancers. Smoking and chewing tobacco can cause cancer of the lungs, throat, and mouth.
Nicotine and Neurotransmitters
Nicotine disrupts the normal relationship between the neurotransmitter acetylcholine and the receptors acetylcholine binds to. These changes in the brain, detailed here with diagrams, can lead to addiction.
Normal acetylcholine and receptors
Nicotine affects the neurotransmitter acetylcholine and its receptor. This receptor is located in many brain structures and body organs. It carries messages related to respiration, heart rate, memory, alertness, and muscle movement.
Too many chemicals in the synapse
Because nicotine is shaped similarly to acetylcholine, it can fit in the same receptors and act just like acetylcholine. After repeated use of nicotine, there is more activity at the acetylcholine receptors than usual because the receptors are being activated by both acetylcholine and nicotine.
Less acetylcholine and fewer receptors
This change in balance causes the brain to “think” there is too much acetylcholine and react by reducing the number of receptors and releasing less acetylcholine into the synapse. The brain now needs nicotine to maintain normal functioning.
Not enough acetylcholine and receptors
These changes in the brain cause a nicotine user to feel abnormal when not using nicotine. In order to feel normal, the user has to keep his or her body supplied with nicotine. This is addiction. If the person stops using nicotine, the number of receptors and their sensitivity to acetylcholine will eventually be reestablished, but only after some time.
Nicotine also causes an increase in the release of dopamine from neurons located in the limbic system. Dopamine is a neurotransmitter responsible for carrying messages about pleasurable feelings. The result is stimulation of the “reward system” in the brain, which causes feelings of pleasure.
The reward system is a circuit in the brain that carries messages about pleasure. These messages move from the dopamine-containing neurons located in the ventral tegmental area (VTA), to a structure in the limbic system called the nucleus accumbens, and then to the prefrontal cortex. Activation of this system causes feelings of pleasure.
Nicotine use also causes a decrease in an enzyme that is responsible for breaking down dopamine. The decrease in this enzyme results in higher-than-normal dopamine levels. Smokers may continue to smoke to maintain these high dopamine levels and the good feelings associated with the drug.
Withdrawal from Nicotine and Nicotine Replacement Therapy
Withdrawal symptoms are the uncomfortable feelings a drug user experiences after he or she has stopped taking a drug. A person who is trying to stop using nicotine may be shaky, have sleeping problems, experience increased appetite, and feel uncomfortable, irritable, and less alert. These unpleasant symptoms can prevent many smokers from quitting.
Nicotine replacement therapy, like the nicotine patch and gum, has helped many smokers quit. These products gradually reduce the amount of nicotine in the brain so that the smoker does not experience the negative effects of a sudden drop in nicotine levels. After the brain has adjusted to nicotine reduction or loss, the withdrawal symptoms can diminish or go away.
Alcohol is found in beer, wine, and hard liquors such as gin, vodka, and whiskey. It affects many areas of the brain and can cause memory loss, impaired motor coordination, impaired thinking and problem solving, changes in emotional behavior, and even death.
Alcohol and Brain Structures
Alcohol affects the frontal lobe region of the brain, causing thinking and problem-solving difficulties. Motor-coordination problems are caused by alcohol’s effects on the cerebellum. Alcohol can cause memory loss by damaging the hippocampus. In large doses, alcohol can cause a person’s heart to stop beating through its effects on the medulla oblongata and the pons.
Alcohol and Neurotransmitters
Alcohol has specific effects on certain receptors and neurotransmitters in the brain.Researchers have found that alcohol affects gamma amino butyric acid (GABA) receptors and GABA, which is the neurotransmitter that binds to them. GABA is an inhibitory neurotransmitter; in other words, it decreases the activity of neurons. More GABA may cause decreased attention, memory alterations, mood changes, and drowsiness.
Alcohol interrupts the normal functioning of other neurotransmitters, and can prevent the neurotransmission that would normally inhibit some types of behavior. For many, this effect causes increased social behaviors (decreased inhibition). Also, like many other drugs of abuse, alcohol increases dopamine release, which is responsible for the pleasurable aspects of drinking.
After long-term use of alcohol, the brain may try to compensate for the inhibitory neurotransmission by increasing excitatory neurotransmission. This increases the activity of other neurons. When alcohol use is stopped, the excitatory neurotransmission is still active, which causes withdrawal symptoms like shaking, sweating, nausea, and anxiety.
Long-Term Damage to the Body
Wernicke-Korsakoff’s disorder is a disease associated with long-term alcoholism. Because alcohol damages the brain, people with this condition cannot form new memories. They also have difficulties with muscle coordination and movement.
Long-term abuse of alcohol can also cause a potentially fatal liver disease called cirrhosis. The liver’s job is to remove poisons, germs, and bacteria from the blood and to help the body function normally. Because alcohol is a poison to the body, the liver works to remove all alcohol that is ingested. When alcohol is repeatedly and excessively used, the liver becomes damaged and this damage can lead to cirrhosis.
Alcohol and Other Drugs
People who abuse alcohol often abuse other drugs as well. In fact, 45 percent of patients being treated for alcohol abuse report abuse of other drugs. Alcohol and certain drugs work in the same areas of the brain. Combining drugs with alcohol can greatly intensify their effects, which can be very dangerous to the brain and body.
Alcohol and Children
Research shows that the younger a person is when he or she begins to drink, the more likely he or she is to develop alcohol problems and alcohol dependence. Drinking at a younger age is also associated with a higher risk of alcohol-related traffic crashes, injuries, fatalities, and violence. In 1984, the United States increased the legal drinking age from 18 to 21 years of age. This change reduced youth drinking and alcohol-related incidents.
Health Benefits of Moderate Drinking for Adults
Research shows that moderate consumption of alcohol has some benefits for adults. For example, moderate alcohol use seems to lower the risk of stroke and heart disease. This may be because alcohol helps keep blood vessels unclogged. “Moderate drinking” is defined as one or two drinks per day for men and one drink a day for women and people over the age of 65. Women and elderly persons of both sexes have lower levels of water, and they absorb alcohol differently than younger men do; thus, a smaller amount of alcohol has stronger effects.