With milk, without sugar

Numerous studies have already shown that caffeine has an antidepressant effect. In most cases, however, no distinction has been made between different types of preparation. A Chinese research group has now done just that. They analysed data from more than 145,000 adults from England, Scotland and Wales who were surveyed between 2006 and 2010 and again in 2016 for the UK Biobank, a large medical database in the United Kingdom.

Almost 20 per cent said they did not drink coffee, around 70 per cent drank one to three cups and the remaining 10 per cent drank more than three cups a day. Depression and anxiety were least common among those who drank two to three cups a day. This was particularly true for ground and unsweetened black coffee and coffee with milk - less so for instant or decaffeinated coffee and when sugar or artificial sweeteners were added.

The optimal amount of coffee could be even higher. This is suggested, for example, by data from around 14,000 adults in Spain. At the beginning of the study - on average they were in their mid-30s - they had not suffered from depression. The risk of developing depression in the following ten years was halved in those who drank at least four cups of coffee a day. In other studies, however, the effects were less pronounced. According to a meta-analysis from 2023 with data from several hundred thousand people, heavy coffee consumption reduced the later risk of depression by around ten per cent.

Coffee as a mood booster

Although these findings come from longitudinal studies, the type of data collection does not actually allow any conclusions to be drawn about cause and effect. It is conceivable that other complaints associated with depression, such as chronic bowel or stomach conditions, could limit consumption.

What suggests a causal relationship, however, is the dose-response relationship that some studies have been able to prove: With every extra cup of coffee a day, the risk of depression also decreases; in the aforementioned meta-analysis, for example, by four per cent per quarter litre, in others even more. Of course, only within certain limits: caffeine intoxication can be fatal.

The antidepressant effect of coffee can also be explained biologically. Caffeine stimulates the central nervous system, it promotes dopamine transmission and blocks adenosine receptors in the brain: it activates and lifts the mood. Other substances in coffee, particularly anti-inflammatory substances, can also contribute to the antidepressant effect.

Caffeine as an anxiolytic

However, there is another, initially seemingly paradoxical explanation for the reduced risk of anxiety in coffee drinkers: caffeine can trigger panic attacks. People who are prone to panic attacks are often aware of this and tend to drink less coffee. In their case, it is not the coffee consumption that reduces anxiety, but the anxiety that reduces coffee consumption.

Experiments confirm the panic-inducing effect. Swedish researchers from Uppsala University compared the effect of caffeine with that of a placebo: around one in two test subjects suffering from panic disorder reacted to caffeine with a panic attack, whereas not a single one reacted to the placebo. On average, it took around five cups of coffee to trigger panic. Among the healthy control subjects, just under two per cent had an anxiety attack. Among other things, caffeine accelerates the heartbeat - a physical process that can contribute to panic attacks.

However, coffee could prevent anxiety that does not manifest itself in panic attacks, such as depression or compulsive disorders. The Chinese research group mentioned above recommends "moderate coffee consumption to prevent and manage anxiety and depression". However, this advice should be taken with a grain of salt: Self-medicating with coffee can backfire.

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