Caffeine’s effect on the brain and caffeine withdrawal

There have been some rather disturbing news items lately concerning people who have ingested too much caffeine in a short period of time and ended up dead.

Because coffee, energy drinks and caffeinated soft drinks are easy to buy, in some cases such as designer coffee drinks seen as chic, and are widely advertised as a good way to get through the day with energy, it seems that such boosts must be harmless and almost accepted as necessary if not normal. Clearly, this phenomenon of using caffeine as an everyday part of the diet has more consequences than just getting an innocuous little mental and physical lift.

Caffeine is chemically addictive. This was established in 1994, and last May, caffeine withdrawal was included as a mental disorder in the fifth edition of “The Diagnostic and Statistical Manual of Mental Disorders.”

Caffeine is both water and fat-soluble, meaning that it dissolves in both water and fat and therefore it can easily pass through the bloodstream and pass into the brain, penetrating the blood/brain barrier.

The chemical structure of caffeine is very similar to a molecule that is naturally present in the brain — adenosine — and therefore caffeine can neatly fit into the brain cell’s receptors for adenosine and thereby block them.

Normally, adenosine produced over time fits into the receptors and produces as feeling of tiredness; however, with caffeine occupying the space, a feeling of alertness and energy occurs lasting for a few hours.

Additionally, dopamine, one of the brain’s natural stimulants, works more effectively when caffeine blocks the adenosine receptors. Moreover, the displaced adenosine cues the adrenal glands to produce another stimulant- adrenaline.

Sounds like a lot of a biochemistry lesson, but the bottom line is that caffeine is a powerful drug and one that blocks the brain’s natural function up to four to six hours per dose until the body can metabolize it and lower its effects.

For those people who ingest caffeine every day, the brain’s chemistry and physical characteristics actually change over time. One occurrence is that the brain cells grow more adenosine receptors in an attempt to regain equilibrium.

This explains why caffeine drinkers can build up a tolerance over time, because the brain tries to compensate and therefore, it takes more caffeine to block the emerging receptors.

The brain also responds by decreasing the number of norepinephrine receptors. Norepinephrine is a natural stimulant. This altered brain chemistry and physiology explains why caffeine withdrawal can be so excruciating.

Within 24 hours of quitting caffeine, the withdrawal symptoms begin. The first symptom is mental fogginess and physical tiredness. Many times, there is a sense of irritability. (I’ve seen those T-shirts warning of early morning conversations).

Soon after the throbbing headache sets in, making it difficult to concentrate, and muscular fatigue, dull muscle aches, nausea and perhaps flu-like symptoms set it. The FDA reports that more than 80 percent of American adults drink or ingest caffeine daily, and many never even contemplate that is a psychoactive substance.

The emergence of energy/sport drinks and caffeine containing diet pills have an increasingly prominent place in sports and recreation and students are more likely than ever fueled by caffeine-laden drinks to take on long hours of study or work.

The underlying chemistry of the caffeine withdrawal is not completely understood but it is surmised that the brain becomes accustomed to operating under a set of conditions imposed by the presence of caffeine and when it is withdrawn, the altered brain chemistry leads to the well-known withdrawal symptoms.

Compared to many other drug addictions, the withdrawal symptoms are relatively short-lived. Usually it takes about a week for your brain to normalize after caffeine cessation. During that time, the brain will decrease the number of adenosine receptors on each cell and revert to the baseline.

A moderate amount of caffeine consumed intermittently is not a problem. Heavy reliance on the drug is. Coffee has about 150 mg of caffeine per 8 ounce cup. Tea has about 75 mg per cup depending on how it is steeped. Green tea has 45 mg.

As for commercial products, you need to read the labels to ensure that you do not overdo the consumption.

It is suggested that you should not exceed about 400 mg of caffeine per day. Even with that, you run the risk of withdrawal symptoms if you don’t get your daily dose, and some people are very sensitive to caffeine and should not take it in even very moderate amounts.


Dr. Jane Riley, Ed.D., certified personal fitness trainer, nutritional adviser, behavior change specialist. She can be reached at, 212-8119 cell/text,


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