Coffee Lovers Become Immune to Caffeine "Buzz," Experts Say
Coffee has a long history of helping tired adults get out of bed in the morning and face a challenging day of work and stress thanks to its believed boost of alertness. Yet a new study conducted by the University of Bristol, U.K., concludes that the "buzz" thought to be generated by caffeine consumption may just be a myth. Instead, researchers claim, caffeine consumption might only bring you back up to "normal" levels of alertness after developing a dependency to it. The study was recently published online in the journal Neuropsychopharmacology.
Researchers believe that habitual coffee drinkers build a tolerance to caffeine’s anxiogenic and stimulatory effects, and therefore do not experience a boost of alertness. Ample research has evidenced the psychostimulant effects of caffeine, but researcher Peter Rogers of the Experimental Psychology Department at Bristol and his team now claim that these effects can only experienced by those who drink little or no coffee or other caffeinated beverages. Those who consume one to six cups of coffee per day instead experience acute caffeine withdrawal symptoms—such as fatigue, headache, and lower levels of alertness—if they abstain and therefore need to consume caffeine to regain baseline levels.
The study included 379 participants who were asked to abstain from caffeine for sixteen hours prior to the experiment. About half of the trial group (162 participants) included non- to low-caffeine consumers, and the other half (217 participants) included medium- to high-caffeine consumers. Participants were either given a 100mg caffeine capsule or placebo capsule containing corn flour. In a double-blind, randomized experiment, participants were tested on their attentiveness, vigilance, and memory by following a series of computer tasks, and also asked to rate their levels of alertness, anxiety, and headache both before and after being given caffeine or placebo.
The medium- to high-caffeine consumers who were given the placebo reported a decrease in alertness and an increase in headache. Those who received caffeine, on the other hand, reported neither. Participants were further tested after being given 150mg of caffeine or a placebo again 90 minutes later. Post-caffeine consumption, these medium- to high-caffeine consumers reported no higher levels of alertness than the non- to low-caffeine consumers who were then given a placebo. The research team concluded that caffeine intake merely brings regular caffeine consumers back up to ‘normal’ levels of alertness, but that no net gain is achieved.
The purpose of the study was to investigate caffeine-induced anxiety disorder, a diagnosis identified in the DSM-IV-TR, and any genetic characteristics in individuals prone to this condition. Individuals who regularly consume little amounts of caffeine demonstrate a link between a variant of the gene ADORA2A, known as rs5751876, and caffeine-induced anxiety disorder. Researchers found that participants with this gene variant were more prone to caffeine-induced anxiety, and were likely to consume slightly higher amounts of caffeine than those without the genotype. For these individuals, consuming caffeine generates a mild increase in anxiety by raising blood pressure, which contributes to their alertness "buzz."
The researchers suggest that substantial tolerance to caffeine’s anxiogenic effect is developed with frequent consumption; although tolerance causes habitual coffee drinkers to consumer higher amounts of caffeine to feel alert, there is no presence of a ‘surplus’ of alertness gained. Rather, habitual caffeine consumers are restoring their normal level of alertness after having experienced the fatiguing effects of caffeine withdrawal.
In their report The Pharmacology of Caffeine (2009), author Dr. Laura Juliano et al. advise that lower levels or elimination of caffeine consumption in individuals with anxiety disorders—such as panic disorder—can help reduce anxiety symptoms. They state: “Acute doses of caffeine generally > 200mg can increase anxiety ratings in both individuals with anxiety disorders [ ] and nonclinical samples [ ], with higher doses sometimes producing unequivocal panic attacks [ ]. Individuals with anxiety disorders appear to be particularly sensitive to the effects of caffeine…[and] tend to report greater anxiety after consuming caffeine than control subjects” (169). They observe that clinically, individuals with anxiety disorders tend to naturally reduce or abstain from caffeine intake, a disparity from Rogers’ latest study’s results.
Regarding caffeine-induced anxiety disorder, Juliano et al. recommend: “Clinicians should consider advising anxiety patients to eliminate caffeine to rule out an etiological role of caffeine in anxiety symptoms” (169).
