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SYDNEY: The sensation of alertness that comes when you enjoy your morning tea or coffee may be an illusion, according to a new study.
Caffeine brings coffee drinkers back to but not above their baseline level of alertness. In fact, frequent coffee drinkers develop a tolerance to both the anxiety-producing effects and the stimulatory effects of caffeine, the researchers report.
“At a personal level the results tell us we don’t gain much, if anything at all, from consuming caffeine. Decaff tea and coffee is a good alternative option,” said psychologist and nutritionist Peter Rogers from University of Bristol.
Anxiety, alertness and headache
In the study, published this week in the journal Neuropsychopharmacology, Rogers and his colleagues asked 379 individuals, the largest study so far, to abstain from caffeine for 16 hours. Then they gave them either caffeine or a placebo.
The study participants then rated their personal levels of anxiety, alertness and headache.
Approximately half of the participants were non or low caffeine consumers and the other half was medium or high caffeine consumers.
The withdrawal reversal explanation
The post-caffeine levels of alertness in the regular coffee drinkers were the same as the non and low consumers who received a placebo, suggesting caffeine only brings coffee drinkers back up to normal.
“It adds further weight to the withdrawal reversal explanation of caffeine effects, while at the same time suggesting anxiety is not an important effect of caffeine for a vast majority of people,” Rogers said.
However, there are side effects for caffeine abstinence among the regular coffee drinkers. When they replaced placebo consisting of cornflower with caffeine, the coffee drinkers reported headaches and low alertness.
The authors also examined the recently discovered link between caffeine-induced anxiety and a specific mutation in the gene ADORA2A.
The researchers hypothesised that people genetically predisposed to caffeine-induced anxiety would be less likely to be frequent caffeine consumers. However, they discovered that people with the gene variant tended to consume slightly larger amounts of coffee.
Constitution not completely ruled out
According to the report it is possible that frequent caffeine consumers could be constitutionally less alert or more fatigued, and they use caffeine to remedy this state of affairs.
“But this is unlikely to be true. We think that the lower alertness of frequent caffeine consumers is due to caffeine withdrawal, not because of their biological inheritance,” said Rogers.
Psychologist Blake McKimmie of University of Queensland has studied the influence of caffeine on participants’ ability to evaluate to a persuasive message, and is not surprised by the results of the study.
Study had only moderate caffeine amount
However, it was only a moderate amount of caffeine that was given to the participants in the recent study, McKimmie said.
The participants were given 100 milligrams and then 150 milligrams, which equals two cups of coffee.
If more caffeine were provided it would not necessarily lead to further improvements: “If they got more caffeine they may well show signs of over stimulation which would interfere with cognition,” McKimmie said.
