Caffeine is a chemical that the body does not need in any capacity for normal functioning, but it causes powerful psychoactive effects once consumed. Caffeine interferes with brain chemistry and hormonal secretions, which can contribute to causing or exacerbating anxiety and depression. Unlike most other psychoactive compounds, caffeine is not regulated, which contributes to its widespread use and addiction.
Biochemistry of Caffeine
Caffeine is absorbed and passes from the blood into the brain fairly quickly. Once in the brain, caffeine interferes with the actions of adenosine, a chemical messenger that has tranquilizing effects, such as reduced neuronal activity. Adenosine essentially dampens anxiety levels, but caffeine counters its actions. Most people consume caffeine because they feel more alert and can go without sleep longer than normal, although chronic use alters brain chemistry and hormone levels. Caffeine stimulates the adrenal glands to secrete stress hormones, such as adrenaline and cortisol, which keeps the body in a "flight or fight" mode. It also stimulates the pancreas to release insulin, which lowers blood sugars and leads to unbalanced metabolism. The effects of caffeine depend on many factors, including tolerance, size, age, stress levels and diet.
Caffeine and Anxiety
Experiments cited in 2008 in "Medical Nutrition and Disease" induced anxiety or panic attacks in patients with panic disorders using the caffeine equivalent of about four to six mugs of coffee. The induced panic attacks were physically and emotionally identical to the spontaneous ones. This points to a fairly strong link between caffeine and stress-boosting hormones. Chronic stimulation of the adrenals can lead to adrenal burn-out, or exhaustion, which is known to cause high anxiety along with profound tiredness, heart palpitations, hypotension and insomnia.
Caffeine and Depression
Short-term, small doses of caffeine can help reduce pain and temporarily alleviate feelings of depression, although larger doses over longer periods of time have depressive effects on most people, as cited in "Biochemistry of Human Nutrition." People who use caffeine regularly report higher depression scores and have more depressive episodes compared to non-users.
In addition to adrenal fatigue, another explanation of why caffeine can cause depression involves serotonin, a brain chemical involved with mood and "happy" feelings. Caffeine depletes B-vitamins, particularly B-6, which is required to synthesize serotonin. Further, chronic caffeine use disrupts sleep cycles and can lead to insomnia. Chronic lack of deep, rejuvenating sleep leads to depression and anxiety, in addition to irritability, reduced immune response and hormonal changes.
Sources of Caffeine
Well-known sources of caffeine include coffee, soda pop and energy drinks. Black tea and green tea contain caffeine, but herbal teas do not. Less well-known sources include pharmaceuticals, chocolate, kola nuts and guarana berries. Decaffeinated coffee has much less caffeine than regular coffee, between 80 and 95 percent less, but it is not totally caffeine-free, according to "Contemporary Nutrition."
References
- "Biochemical, Physiological and Molecular Aspects of Human Nutrition"; Martha Stipanuk; 2006
- "Medical Nutrition and Disease: A Case-based Approach"; Lisa Hark; 2008
- "Biochemistry of Human Nutrition"; George Gropper; 2000
- "Human Biochemistry and Disease"; Gerald Litwack; 2008
- "Contemporary Nutrition"; Gordon M. Wardlaw; 2010
