If you missed your morning coffee and now you have a headache and difficulty concentrating, you might be able to blame it on caffeine withdrawal. 

In general, the more caffeine consumed, the more severe withdrawal symptoms are likely to be, but as little as one standard cup of coffee a day can produce caffeine addiction, according to a Johns Hopkins study that reviewed over 170 years of caffeine withdrawal research. 

Results of the Johns Hopkins study should result in caffeine withdrawal being included in the next edition of the DSM or the Diagnostic and Statistical Manual of Mental Disorders, considered the bible of mental disorders, and the diagnosis should be updated in the World Health Organization's ICD, or The International Statistical Classification of Diseases and Related Health Problems.

The researchers identified five clusters of common withdrawal symptoms: headache; fatigue or drowsiness; dysphoric mood including depression and irritability; difficulty concentrating; and flu-like symptoms of nausea, vomiting and muscle pain or stiffness.  In experimental studies, 50 percent of people experienced headache and 13 percent had clinically significant distress or functional impairment -- for example, severe headache and other symptoms incompatible with working.  Typically, onset of symptoms occurred 12 to 24 hours after stopping caffeine, with peak intensity between one and two days, and for a duration of two to nine days.  In general, the incidence or severity of symptoms increased with increases in daily dose, but abstinence from doses as low as 100 milligrams per day, or about one small cup of coffee, also produced symptoms.

The research also showed that avoidance of caffeine withdrawal symptoms motivates regular use of caffeine.  For example, the satisfying feelings and perceived benefits that many coffee users experience from their morning coffee appear to be a simple reversal of the negative effects of caffeine withdrawal after overnight abstinence.

According to the report, caffeine is the most widely used behaviorally active drug in the world.  In North America, 80 percent to 90 percent of adults report regular use of caffeine.  Average daily intake of caffeine among caffeine consumers in the United States is about 280 milligrams, or about one to two mugs of coffee or three to five bottles of soft drink, with higher intakes estimated in some European countries.  In the United States, coffee and soft drinks are the most common sources of caffeine, with almost half of caffeine consumers ingesting caffeine from multiple sources, including tea.

Reference Source 140
November 4, 2005