If you drink lots of coffee regularly you will most probably not experience the boosting effects of caffeine, compared to others who drink coffee in moderation – in fact, you may be consuming your caffeine to avoid the withdrawal symptoms of drowsiness and headaches. A study published in the journal Neuropsychopharmacology say that using coffee as a pick-me-up may be futile if you drink it all the time.

The scientists, from the UK and Germany, wrote that individuals who consume a lot of caffeine may develop a tolerance to its stimulatory effects, which may only work in those unused to coffee.

The researchers asked 379 volunteers to abstain from coffee for 16 hours. 217 of the participants were classed as medium to heavy coffee drinkers, meaning they drank at least 1, and up to 6 cups per day – 162 were either non-coffee drinkers, or consumed very little of it.

On the following day half of the participants were given a coffee expresso, 100mg dose of caffeine, while the other half received a drink containing no caffeine. The researchers found that:

  • Those in the medium to heavy coffee drinking group who were given a non-caffeine drink reported a drop in alertness, and more headaches.
  • Those in the medium to heavy coffee drinking group who were given a caffeine drink did not report a drop in alertness or increase in headaches. However, their levels of alertness were no higher than the habitual non-coffee drinkers or low consumers who received a placebo.

The scientists believe that this suggests that caffeine only brings the medium to heavy coffee drinking people back up to a baseline or normal level – but does not boost them.

Even so, it can be argued that the habitual coffee drinker needs his/her coffee to avoid drowsiness or headaches; this supports the researchers’ suggestion that heavy consumers of coffee or tea do so to avoid withdrawal symptoms.

Professor Peter Rogers and team said:

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.

The authors concluded:

With frequent consumption, substantial tolerance develops to the anxiogenic effect of caffeine, even in genetically susceptible individuals, but no net benefit for alertness is gained, as caffeine abstinence reduces alertness and consumption merely returns it to baseline.

“Association of the Anxiogenic and Alerting Effects of Caffeine with ADORA2A and ADORA1 Polymorphisms and Habitual Level of Caffeine Consumption”
Peter J Rogers, Christa Hohoff, Susan V Heatherley, Emma L Mullings, Peter J Maxfield, Richard P Evershed, Jürgen Deckert and David J Nutt
Neuropsychopharmacology advance online publication 2 June 2010; doi: 10.1038/npp.2010.71

Written by Christian Nordqvist