Coffee ranks among the world’s most popular beverages, and its physiological impacts—from improved longevity to reduced cardiovascular disease—are well-known. But its impact on psychological health is less understood. Despite some studies finding that drinking coffee appears to reduce symptoms of depression, the link between caffeine and mood disorders is muddy—the popular beverage may affect different people in different ways.
Caffeine is one of the most commonly consumed stimulants across the globe, and for good reasons. In moderation, it can boost your mood and energy levels, improve concentration, and enhance physical performance. If you’re a person who’s sensitive to caffeine, however, evidence suggests that drinking too much java may lead to irritability, anxiety, and even depressive symptoms, according to the Mayo Clinic.
Here’s what the science says about how coffee affects mental health.
Too much of a good thing
Let’s start with the basics: Too much caffeine can cause problems with your sleep. Daniel K. Hall-Flavin, MD, of the Mayo Clinic, points out that disrupted sleep can worsen depression. Hall-Flavin also notes that caffeine can worsen symptoms in those suffering from anxiety disorders. Given that anxiety and depression often co-exist, consuming caffeine may fuel the latter.
According to an article in Medical News Today, drinking coffee excessively can lead to adverse side effects like anxiety, increased blood pressure, headaches, heart palpitations, nausea, restlessness, agitation, tremors, and nervousness—all of which can have a negative impact on mood. These are all symptoms that mimic the body’s “fight or flight” response to potential threats, which most stimulants can trigger.
This idea is supported by the findings of a study published this year in Cureus, which examined the relationship between caffeine intake and anxiety and depression among college students. Researchers followed a cohort of 114 American college students, who filled out surveys detailing their levels of caffeine consumption and general mental health.
Depressive symptoms (including eating disorders, sleep disorders, and depressed mood) and anxiety were both more likely in those with greater caffeine intake. While many previous studies have found inverse associations between caffeine intake and depression—suggesting that it may serve as a protective agent—all of those studies were conducted on individuals aged 40 or older. Conversely, a review of articles examining caffeine intake by children and young people found a positive association between caffeine intake and depression.
The study’s authors conceded that there’s still no clear evidence that caffeine causes depression, but posited that caffeine may inhibit adenosine receptors in the central nervous system, primarily in the hippocampus, amygdala, and prefrontal cortex, which are areas of the brain associated with emotion. This may affect anxiety when caffeine intake is excessive, particularly in those with a genetic predisposition that makes them sensitive to caffeine.
Disruption to neurotransmitters
The Cureus study is not the only research to suggest that caffeine’s disruption of neurotransmitters may result in alterations to mood and detrimental impacts on mental health. A review published in the International Journal of Preventive Medicine found that tea and coffee disrupt dopamine and gamma-aminobutyric acid (GABA) neurotransmitters, which can lead to depression and irritability, respectively.
Likewise, a review published by ScienceDirect, looked specifically at caffeine’s impact on the modulation of neurotransmitters. Authors found evidence that, in moderation, caffeine consumption can help reduce the symptoms of depression in women. However, they also found that, at high doses, caffeine can cause insomnia, agitation, nervousness and other adverse symptoms. Researchers cited studies that found patients with generalized anxiety disorders were more sensitive to caffeine, and that caffeine can exacerbate the symptoms of certain neuropsychiatric disorders.
Similarly, a study published in Physiology and Behavior found that the chronic consumption of caffeine can induce anxiety and may exacerbate symptoms of PTSD. Researchers examined the impacts of caffeine on rats, which had been subjected to stressful experiences, including restraint and forced swimming. After dosing the rats with caffeine, they monitored their levels of stress hormones.
They found that caffeine aggravated depressive and anxiety-like behavior, which had been induced by the stressful experiences. Additionally, caffeine consumed by rats that hadn’t been subjected to stressful experiences exhibited PTSD-like symptoms, suggesting that caffeine alone is enough to trigger a stress reaction.
Much of this evidence suggests that caffeine aggravates pre-existing symptoms of depression or anxiety, so if you suffer from either condition, you might want to limit or avoid caffeinated beverages. But if you’re a heavy coffee-drinker who’s in good physical and mental health, it’s still worth considering how caffeine withdrawal symptoms can affect you.
According to Dr. Hall-Flavin of Mayo, abruptly quitting caffeine following the development of a heavy habit can result in “a depressed mood until your body adjusts.” You may also experience other symptoms like headaches, fatigue, and irritability.
As such, even if you have a constitution that can handle a regular caffeine intake, think twice before going cold turkey. Instead, aim to gradually reduce the amount of caffeinated beverages you’re consuming.
Learn more about the effects of coffee and tea on health at MDLinx.