Caffeine is the world’s most popular psychoactive substance. So many of us love it a la Starbucks, Tim Hortons or just out or our home coffee machine. Me, I love coffee and I’m a fan of caffeine too. Coffee’s the nectar of the gods and nothing will convince me otherwise.

It seems though, caffeine can actually hurt you. I know, I never thought my beloved coffee could harm me, but I suppose anything that you abuse, will abuse you back. So, here is everything you ever needed to know about caffeine, caffeine disorders and caffeine and mental illness but were afraid to ask.

Caffeine-Specific Psychiatric Disorders

There are four recognized caffeine disorders in the DSM-IV:

  • Caffeine intoxication
  • Caffeine-induced anxiety disorder
  • Caffeine-induced sleep disorder
  • Caffeine-related disorder NOS (not otherwise specified)

These caffeine disorders are pretty much just like they sound, they include symptoms like:

  • Restlessness
  • Nervousness
  • Insomnia
  • Anxiety
  • Tachycardia

To be diagnosed with a caffeine disorder it must produce significant harm and not be explained by another disorder. These disorders tend to appear in people consuming large amounts of caffeine. “Large” varies by person, but is generally at least six cups of coffee per day (many times much, much more).

These disorders aren’t very interesting to me, I’m mostly interested in how caffeine impacts other disorders. (Oh, and yes, it is possible to die from a caffeine overdose but you’d really have to work at it.)

Caffeine and Depression

This is a bit of a contentious subject. There seems to be large numbers of people online claiming that caffeine can severely impact depression, but they say this without any real supporting data. I have yet to find a reputable study that shows a significant causal link between caffeine and depression.

However, that being said, caffeine is thought to be an adenosine receptor antagonist (stay with me) which likely indirectly increases norepinephrine, dopamine and serotonin activity. These are the same neurotransmitters that many antidepressants target. This might explain why some studies actually find that caffeine improves mood:

These benefits seem to be related to adaptation of mental energy to the context by increasing alertness, attention and cognitive function . . . 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.

No, I’m not suggesting you try using coffee as an antidepressant.

Caffeine and Anxiety

This is the one real bad news part of the story. Basically if you’re suffering from anxiety, caffeine will make you feel worse. People who don’t normally feel anxious generally do not report anxiety from the effects of caffeine, but those with anxiety disorders do report greater anxiety from caffeine.

Patients with panic disorder and performance social anxiety disorder seem to be particularly sensitive to the anxiogenic effects of caffeine…

Interestingly, the same study states people with OCD, which is part of the anxiety disorder spectrum, actually can benefit from caffeine intake. It’s really all very confusing.

It’s also worth noting if you’re anxious and intaking caffeine, benzodiazapines (like Valium or Xanax) don’t work as well, so the anxiety created by caffeine can’t even really be treated. You have just get off the caffeine. Sorry.

Caffeine, Psychosis and Antipsychotics

Coffee, Caffeine and DepressionVery large amounts of caffeine have been known to destabilize bipolars and schizophrenics inducing mania or psychotic episodes. This isn’t terribly prevalent but is known to occur.

Caffeine is also known to interfere with some antipsychotic medication, generally first generation antipsychotics, specifically clozapine. Antipsychotic dosage generally has to be increased to account for this interference.

This interference isn’t present in second-generation antipsychotics but caffeine can increase the blood level of these drugs which can increase side-effects.

No matter what, if you’re on an antipsychotic and like your coffee/tea/pop, your doctor should know about it.

Caffeine and Suicide

There is an interesting link between increased caffeine and nicotine intake with suicide. This is not a causal link (caffeine and nicotine do not cause suicide) but there is a correlational link. It seems if you see someone injesting large amounts of caffeine and nicotine this is warning signal for suicide in someone with a mental illness. (Reference 1 and reference 2.) This was found in both bipolar and schizophrenia.

Caffeine and Mental Illness In Short

Basically, unless you’re already anxious or prone to psychosis or mania, caffeine is not harmful in moderation. There is even evidence to suggest it helps with certain tasks.

I say, ignore the freaked-out internet people and enjoy a morning latte. I do.