Coffee is the most commonly consumed drink in the United States. In 2015, Americans spent $72.4 billion on coffee. 64% of Americans over 18 said they’d had a cup of coffee within the past day in a National Coffee Association survey. As of 2010, American coffee drinkers had an average of three 9-ounce cups per day. And although the US is near the top, there are a number of countries that actually consume more coffee per capita.
Just a generation or two ago, coffee had a bad reputation. People didn’t seem to care too much, as they continued to chug coffee each day, but there was an underlying assumption that it wasn’t very healthy. It's time to revisit this assumption, as beliefs about coffee’s physical and psychological effects have swung noticeably in the past two decades and studies continue to pour in.
A number of myths about coffee persist, though they’ve been debunked– among them the beliefs that coffee dehydrates you, stunts your growth, or is truly addictive. More importantly, new studies suggest a link between regular coffee consumption and a lower risk of conditions like heart disease, type 2 diabetes, and prostate cancer. And it improves exercise performance and endurance. These studies, which are appearing more and more frequently, are usually based on moderate consumption of no more than 4 cups of black coffee per day.
In August 2017, a giant study of over 500,000 people in ten European countries who had been in for regular check-ins since the 1990s revealed a “reduced risk of death from various causes” for coffee drinkers compared to non-drinkers. Similarly, an umbrella review of 218 meta-analyses (that’s a lot of research) from the BMJ concluded:
Coffee consumption seems generally safe within usual levels of intake, with summary estimates indicating largest risk reduction for various health outcomes at three to four cups a day, and more likely to benefit health than harm.
There are always caveats, and certain health factors like osteoporosis and pregnancy are mentioned in multiple studies as a potential reason to avoid coffee. Like anything, coffee has negative effects. It may increase the amount of acid in your stomach, block calcium absorption, and increase blood pressure. It can have you running to the bathroom (for multiple reasons) at higher doses. Withdrawal symptoms are annoying at best, and many people simply find coffee’s effects to be too intense. Plus, coffee can become a pretty expensive habit.
This isn’t as an endorsement of coffee. Don’t try it because of this blog post. It’s always good to check with your doctor if you have preexisting conditions, and to take any negative reactions seriously.
But what about mental health?
Physical and mental health, as we all know, are closely related. It wouldn’t make much sense to think about the effects of coffee on mental health without considering the things above, which can certainly alter our mental state. Mental health is a direct result of our physical condition, and vice versa.
If you’ve had too much coffee or you can remember your first time drinking it, there’s a good chance you know the jittery, anxious feeling it can bring. But what does coffee do to your brain, and do these effects add up to changes in our mental health? Is it bad to drink coffee when you have a mood or anxiety disorder, OCD, schizophrenia, and so on?
We'll need to start with an understanding of how caffeine affects us. According to the American Psychological Association:
Caffeine is chemically similar to the neuromodulator adenosine, which accumulates through the day and induces drowsiness for sleeping at night. When we consume caffeine, it binds to adenosine receptors in the brain, blocking the effects of adenosine, with the side benefit of allowing dopamine to flow more freely. That can bring on feelings of well-being, energy and alertness.
Although it’s about 98% water, coffee contains over 1,000 chemicals. Most researchers focus on caffeine, which is believed to account for most of coffee’s effects on the brain. Caffeine is a very common stimulant, found naturally in dozens of plants, most notably coffee, tea, kola, and mate. It reduces fatigue and seems to improve performance on some tasks, especially for tired people, while making other tasks harder.
The same BMJ article from above says coffee “consumption had a consistent association with lower risk of depression and cognitive disorders, especially for Alzheimer’s disease.” Although some believe caffeine might encourage depression symptoms, an extended analysis by Chinese researchers suggests an occurrence of under 1% for caffeine-related depression, and concludes that “coffee and caffeine consumption were significantly associated with decreased risk of depression.”
On the other hand, drinking coffee isn’t a treatment for depression. And because it might cause sleep problems in some people, coffee can worsen mood; plus, withdrawal symptoms can exacerbate existing irritability and fatigue. Research on depression and caffeine is still in its early stages, so it’s best not to initiate a coffee habit based on any single study.
Yet another study from the Journal of Alzheimer’s Disease links moderate caffeine intake (fewer than 6 cups of coffee each day) to a lower risk of suicide. But the authors also have this to say:
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 evidence suggest that it may be effective for some patients with obsessive-compulsive disorder.
This last part is counterintuitive, and it seems like the kind of claim that would require more research. Most clinicians (and common sense) would suggest that someone with OCD or an anxiety disorder should limit their coffee intake as much as possible. Other studies point to abnormal caffeine sensitivity in people with GAD, and suggest that coffee increases cortisol levels while creating “behavioral effects… similar to those experienced during panic attacks.”
But in a small study, seven of twelve patients with OCD saw “immediate improvement” on 300 milligrams of coffee daily. The author suggests that caffeine may work better in one concentrated dose each morning than spaced out throughout the day, and reminds us that caffeine remains a “well-known anxiety producer in many people.”
Some clinicians have interesting approaches to addressing the anxiogenic, or anxiety-producing, effects of coffee in their patients: telling them to drink more of it. Norman B. Schmidt, PhD, tells patients with panic disorder who drink coffee and then become anxious to drink more coffee. This isn’t because he thinks it’ll help. He wants these patients to experience a stronger unpleasant effect and learn by feeling that their symptoms are closely tied to coffee consumption.
A few studies suggest that most people self-regulate their coffee consumption, learning to avoid drinking coffee to the point of becoming anxious. A study involving 43 patients suggests that people with anxiety disorders “have increased caffeine sensitivity, which leads to decreased consumption.”
Medication is another complicating factor. There are almost 100 known contraindications between caffeine and prescription drugs, whether it enhances the drug, creates further side effects, or makes the drug less effective. Many anti-anxiety drugs, sleeping pills, and mood stabilizers fall into this last category.
A 2005 Cambridge study found that “psychiatrists rarely inquire about caffeine intake when assessing patients… Caffeine is implicated in the exacerbation of anxiety and sleep disorders, and people with eating disorders often misuse it.” The authors are suggesting that coffee doesn’t cause or constitute a disorder, but can certainly exacerbate one. They go on, with a focus on schizophrenia: “In psychiatric in-patients, caffeine has been found to increase anxiety, hostility and psychotic symptoms.”
The big book of psychiatric disorders, the DSM-5, lists caffeine intoxication disorder and caffeine withdrawal among its hundreds of conditions. Symptoms of caffeine intoxication include restlessness, nervousness, excitement, insomnia, gastrointestinal disturbance, rambling flow of thought and speech, cardiac arrhythmia, periods of high energy, and psychomotor agitation. Importantly, to merit diagnosis, “these symptoms must cause distress or impairment in social, occupational and other forms of functioning, and not be associated with other substance, mental disorder or medical conditions.”
Although it seems like the DSM committee was mostly interested in raising awareness about how common caffeine intake is and the ways it can negatively impact someone's life, a number of experts were confused about the DSM's concept of caffeine-related disorders. They pose some good questions: can we consider something a disorder when intoxication lasts less than a day? Can coffee drinking really become a substance use disorder like the other ones? Is it reasonable to create another disorder for people who drank too much coffee?
Matt Collins, a direct support professional working in a group home for individuals with developmental disabilities who also has OCD, says it well in one of his blog posts:
While the verdict is still out on whether caffeine exacerbates OCD symptoms or actually alleviates them, it seems that coffee probably does more harm than good for people with anxiety. The problem is, I love coffee… Sometimes it feels like coffee is the only thing that makes me happy during a flare-up.
If all of this research seems a bit contradictory, it is. Like almost anything in science, there’s no conclusive verdict about coffee. Although it’s worth keeping an eye on all the research that’s sure to emerge in the next few years, there will always be a lot of variance in coffee habits, its effects, and tolerance from one person to the next. We tend to conflate the effects of drinking coffee with the effects of drinking “way too much” coffee, and it’s important to separate these things out when trying to make informed decisions. We know there's a big difference between drinking one glass of wine and seven glasses; so why do we tend to think in extremes when it comes to coffee?
Is coffee necessarily bad for you? No, not for most people. As with any diet advice, we have to look beyond all the absolute statements with unclear origins telling people to drink a ton of coffee or avoid it completely. But is it good for you? It depends who you are, and what you think is good for you.