Caffeine, Mental Health, and Psychiatric Disorders

Abstract

Abstract. Caffeine intake is so common that its pharmacological effects on the mind are undervalued. Since it is so readily available, individuals can adjust their own dose, time of administration and dose intervals of caffeine, according to the perceived benefits and side effects of each dose. This review focuses on human studies of caffeine in subjects with and without psychiatric disorders. Besides the possibility of mild drug dependence, caffeine may bring benefits that contribute to its widespread use. These benefits seem to be related to adaptation of mental energy to the context by increasing alertness, attention, and cognitive function (more evident in longer or more difficult tasks or situations of low arousal) and by elevating mood. Accordingly, moderate caffeine intake (< 6 cups/day) has been associated with less depressive symptoms, fewer cognitive failures, and lower risk of suicide. However, its putative therapeutic effects on depression and ADHD have been insufficiently studied. Conversely, in rare cases high doses of caffeine can induce psychotic and manic symptoms, and more commonly, anxiety. Patients with panic disorder and performance social anxiety disorder seem to be particularly sensitive to the anxiogenic effects of caffeine, whereas preliminary data suggests that it may be effective for some patients with obsessive compulsive disorder (OCD). The threshold for the anxiogenic effect of caffeine is influenced by a polymorphism of the A2A receptor. In summary, caffeine can be regarded as a pharmacological tool to increase energy and effortful behavior in daily activities. More populational (cross-sectional and prospective) and experimental studies are necessary to establish the role of caffeine intake in psychiatric disorders, especially its putative efficacy on depressive mood and cognitive/attentional disorders.

Adenosine Signaling in Anxiety

“…Interestingly, despite being anxiogenic in Wistar rats in the elevated plus maze, caffeine actually increased open arm time after the rats underwent a chronic, unpredictable stress procedure (Pechlivanova et al, 2010), a method to model depression in rodents. This reduction in anxiety-like behavior by caffeine in the context of depression may be related to other evidence suggesting that moderate caffeine intake (< 6 cups/day) was associated with less depression and a lower risk of suicide (Lara, 2010). This suggests that different mechanisms may underlie the pathogenesis of anxiety and depression, despite their cooccurrence in many psychiatric diseases, and that both may involve changes in adenosine signaling.…”

“…Research has revealed that adenosine signaling is central to the anxiety regulating effects of these drugs. While people can benefit from many of the effects of adenosine receptor antagonism by caffeine, such as increased alertness, improved attention or focus, and even amelioration of depressive symptoms (Lara, 2010), sensitivity to caffeine-induced anxiogenesis may preclude certain individuals from enjoying coffee, tea, cola, or chocolate. On the other hand, moderate doses of alcohol are anxiolytic, and sensitivity to this effect may lead a person to abuse alcohol.…”

“…Conversely, adenosine receptor antagonism is responsible for the anxiogenic responses elicited by moderate to high doses of caffeine, theophylline (Imaizumi et al, 1994;Kulkarni et al, 2007;Pechlivanova et al, 2010), or other adenosine receptor antagonists (Imaizumi et al, 1994;Florio et al, 1998;Koetter et al, 2009;Zhao et al, 2009) in rodents and humans (Lara, 2010). It has also been suggested that the anxiolytic effect of the adenine derivative BWA78U in the LD box involves adenosine receptor activation (Willard et al, 1990), and that adenosine is the active principle in the Longan Arillus extract (Okuyama et al, 1999), a traditional Asian remedy for mild anxiety.…”

Concluding Remarks

“…One of the most prevalent complications of AD is depression of mood, and the recent observations that caffeine might be a mood normalizer are of particular interest [29]. Given that the consumption of caffeine is associated with a reduced risk of depression [30], this may be a further potential confounding factor to be taken into account when designing a study to probe the ability of caffeine to preserve memory function in AD patients.…”

“…Given that the consumption of caffeine is associated with a reduced risk of depression [30], this may be a further potential confounding factor to be taken into account when designing a study to probe the ability of caffeine to preserve memory function in AD patients. Likewise, several other beneficial effects of caffeine on arousal and motivation [31,32] as well as other psychiatric conditions [29] should also be considered.…”