NRSC 4132 Blog

How effective is your caffeine in the morning?
"Caffeine, a widely consumed adenosine A1 and A2A receptor antagonist, is valued as a psychostimulant, but it is also anxiogenic. An association between a variant within the ADORA2A gene (rs5751876) and caffeine-induced anxiety has been reported for individuals who habitually consume little caffeine." How many cups do you drink in the morning before you feel like you are ready to take on the day? The average intake of caffeine is on average was 346 mg per day (equivalent to about three cups of ground coffee per day). What if I were to tell you that the coffee you are drinking scientifically isn?t helping that fatigue. "Although frequent consumers feel alerted by caffeine, especially by their morning tea, coffee, or other caffeine-containing drink, evidence suggests that this is actually merely the reversal of the fatiguing effects of acute caffeine withdrawal (James and Rogers, 2005; Sigmon et al, 2009)."

What if I were to tell you that caffeine has a negative side effect to your health, would you continue to drink it? Caffeine has been linked to hypertension, increased anxiety, nervousness, irritability and nausea. So why can coffee taste that good but have some many side effects? "These behavioral and physiological effects of caffeine occur primarily through antagonism by caffeine of the action of endogenous adenosine at adenosine A1 and A2A receptors (Fredholm et al, 1999)." This study has linked a SNP between caffeine and increased anxiety. "Specifically, it was found that 150 mg caffeine (equivalent to the amount of caffeine present in, eg, 1½ cups of ground coffee) increased anxiety in individuals carrying the TT genotype of the ADORA2A SNP rs5751876, but not in the CT and CC genotype groups (Alsene et al, 2003; Childs et al, 2008)." This study took 218 women and 198 men and administered two doses of caffeine 100mg in the morning and 150 mg shortly after. There was randomization on who would receive caffeine and who would have a placebo. The group of people took a pre-survey to make sure that all caffeine users drank approximately the same amount of caffeine. The day before the study, subjects were not allowed to drink anything that had caffeine in it. Surveys were given to check the anxiety, alertness and quality of headache.

"Another key finding of this study is that a clear anxiogenic effect of caffeine, larger i individuals with the ADORA2A rs5751876 TT genotype, was observed only for people who habitually consumed little or no caffeine (the N and L groups). Higher caffeine consumption appears to lead to substantial tolerance to this effect." They discovered that people who continue to drink caffeine at a high enough rate didn't experience the increased side-effects. They discovered that the subjects developed a tolerance to the caffeine. "Although frequent caffeine consumers experience minimal increased anxiety after caffeine consumption, they are at risk of at least two clear adverse effects of acute caffeine abstinence, namely low alertness and increased headache."

To sum it up people who are habitual users do not develop adverse side effects until they withdraw from the caffeine use. There is also research that has linked a SNP to increased anxiety secondary to caffeine assumption.
For reading of full article please visit http://www.nature.com/npp/journal/v35/n9/full/npp201071a.html