Caffeine is among the most widely used central nervous system stimulants. The effects caused by this drug are similar to those of other stimulants, such as amphetamine and cocaine. Consuming caffeine speeds up brain activity and makes a person more alert. Harvard Health Publications says that caffeine effects can be felt approximately 15 minutes after it enters the body and take up to six hours to completely disappear.
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According to DiscoveryHealth.com, caffeine affects the brains mainly by binding to certain receptors in the brain. This makes it impossible for a chemical called adenosine to bind with these receptors. Normally, this chemical would cause drowsiness and slow down neural activity, but since caffeine is blocking receptors that usually function with adenosine, the effect is the opposite, making neurons more active than usually.
Affects Hormone Release
DiscoveryHealth.com states that after caffeine has caused an increase in the activity of adenoside receptors, the pituitary gland responds by releasing hormones. These hormones cause the adrenal glands to produce adrenaline. This hormone causes what is called the "fight or flight" response. It makes the brain and the body of the person ready to defend itself in case of emergency. Thus, the person becomes very alert and is able to work rapidly.
Increases Dopamine Production
According to DiscoverHealth.com, a very large amount of caffeine can also activate the brains' rewards centers. Increased activity of this area is also associated with stimulant drugs such as amphetamine or heroine. The brains' reward center soon starts pumping out more dopamine. Dopamine is a neurotransmitter that causes a feeling of reward and happiness. It is this neurotransmitter that is often said to cause addiction. In the long run, a person builds tolerance to any drug and will start to require increasingly larger doses of caffeine.
Activation of Frontal Lobes
Dr. Florian Koppelstaetter and colleagues from the Medical University Innsbruck in Austria presented a study in 2005 that showed caffeine consumption activates the frontal lobes of the brains. These areas are responsible for short-term memory and attention. Thus, caffeine can increase these functions in a person.
Slowed Hippocampus Function
The long-term effects of caffeine are not so pleasant. Dr. Han Me and colleagues from Pusan National University in Korea reported in a 2005 study published in “Biochemical Biophysical Research Communication Journal” that long-term consumption of low doses of caffeine slowed the functions of hippocampus. This area in the brain is responsible for long-term memory and learning. The authors concluded that although caffeine might improve person’s alertness for a short period of time, it actually slows down the learning and memory via decreasing the function of hippocampus.