caffeine and anxiety

There is no limit to how far molecular biology is extending to explain biological phenomenon. This is a brilliant example of hw such studies can explain. Some people are very susceptible to caffeine and become anxious. Others aren’t. This paper explains a possible reason.
Association between ADORA2A and DRD2 Polymorphisms and Caffeine-Induced Anxiety
Caffeine produces mild psychostimulant and sometimes anxiogenic effects by antagonizing adenosine at A1 and A2A receptors, and perhaps through interactions with other transmitter systems. Adenosine receptors are colocalized and functionally interact with dopamine receptors in the brain. Thus, functional polymorphisms in the genes for either adenosine or dopamine receptors may affect responses to caffeine. In this study, we examined associations between self-reported anxiogenic effects of caffeine and variation in the genes for A2A (ADORA2A) and DRD2 (DRD2) receptors. Healthy male and female individuals (n=102), who consumed less than 300 mg caffeine per week, ingested capsules containing 0, 50, 150, and 450 mg caffeine under double-blind conditions in four separate experimental sessions. Subjective anxiety was measured before and at repeated times after capsules were consumed. At the 150 mg dose of caffeine, we found a significant association between caffeine-induced anxiety (Visual Analog Scales, VAS) and ADORA2A rs5751876 (1976C/T), rs2298383 (intron 1a) and rs4822492 (3′-flank), and DRD2 rs1110976 (intron 6). Caffeine-induced anxiety (VAS) was also associated with two-loci interactions of selected ADORA2A and DRD2 polymorphisms. The lowest dose of caffeine did not increase ratings of anxiety while the highest dose increased anxiety in the majority of subjects. These findings provide support for an association between an ADORA2A polymorphism and self-reported anxiety after a moderate dose of caffeine. It is likely that other ADORA2A and DRD2 polymorphisms also contribute to responses to caffeine.
Childs,Hohoff, Deckert, Ke Xu, Badner and de Wit ( 2008) Association between ADORA2A and DRD2 Polymorphisms and Caffeine-Induced Anxiety. Neuropsychopharmacology (2008) 33, 2791–2800; 27 February 2008

Martin Eastwood
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