The Institute for Scientific Information on Coffee (ISIC) has evaluated the suggested association between coffee consumption and anxiety.

Anxiety is a feeling of nervousness, dread, apprehension, and worry. Mild anxiety is vague and unsettling, while severe anxiety can be extremely debilitating and considered a disorder.

Existing research exploring the association between coffee consumption and anxiety has varying conclusions, including:

• Caffeine seems to have no effect on anxiety in some individuals whilst in others, particularly at moderate (150mg caffeine) levels of intake, caffeine may increase anxiety.1
• In high and low anxiety sensitive individuals, similar alertness and symptom reports were shown following caffeine ingestion. Respiratory symptoms were more marked when caffeine was expected and administered in the low anxiety sensitive group and when caffeine was unexpectedly administered in the high anxiety sensitive group.2

Overall, the body of scientific evidence to date suggests that caffeine may be associated with an increase in anxiety at moderate levels of intake (150mg caffeine – approximately two cups of coffee) in individuals who are predisposed to this effect, and that symptoms of anxiety are less likely to be seen at lower levels of caffeine intake. It is thought that the adenosine receptor system, which mediates the psychoactive effects of caffeine, is involved in the regulation of anxiety, although the precise mechanism is unknown at present.3,4

Research suggests that there may be a genetic component to this sensitivity, explaining why only some individuals appear to experience an effect, however further research is required to confirm these effects.3 It is worth noting that with frequent consumption, substantial tolerance develops to the anxiety-inducing effect of caffeine, even in genetically susceptible individuals, and therefore the association does not tend to affect levels of coffee consumption.3