Nicotine is an addictive substance that causes changes in the brain. According to the Mayo Clinic, nicotine produces mood-altering effects in the brain in addition to potential health problems. The brain is comprised of nerve cells that communicate through chemicals called neurotransmitters. The neurotransmitters are essential in many functions of the body such as thinking, memory, mood and pain. Nicotine use produces changes in the way the neurotransmitters function, thus altering normal processes in the brain.
Nicotine Affects Acetylcholine
Acetylcholine is a neurotransmitter of the nervous system that has an important role in sensory perception, alertness and attention. Nicotine molecules are shaped like acetylcholine and, when nicotine is inhaled, it attaches to acetylcholine receptors in the brain. Nicotine mimics the acetylcholine, which then causes the real acetylcholine to overwork while nicotine is present. After nicotine courses through the body, the acetylcholine is depleted from the brain, often leading to a feeling of fatigue, mental slowness or low mood. The National Institute on Drug Abuse (NIDA) indicates that this alteration of the acetylcholine may further impact the potential for long-term addiction to nicotine, virtually leading the body to crave the substance to supplement the depleted neurotransmitter.
Reward in the Brain
Nicotine activates additional neurotransmitters in the brain that are responsible for rewards and pleasures. The neurotransmitter dopamine is increased during use of nicotine, causing an initial sense of euphoria. Science Daily further reports a study from the National Institutes of Health titled "Scientists Identify Brain Regions Where Nicotine Affects Attention." It concluded that the parietal cortex is activated through use of nicotine. The initial result of parietal cortex activation is improved alertness and attention, but this also is a region of the brain that may be impacted, once the brain depends on the nicotine.
Additional Brain Regions
Nicotine is also thought to stimulate the hippocampus and cortex of the brain. The hippocampus is located within the limbic system of the brain. The hippocampus plays a role in long-term memory, thought and attentiveness. The cortex has two parts--the motor cortex and the sensory cortex. The motor cortex regulates movement while the sensory cortex process information received from the senses, such as the eyes, touch and smell. The Canadian Institute of Health Research indicates that the effect of nicotine on the hippocampus and cortex may further explain the vigilance and attentiveness often reported by nicotine smokers.
