Caffeine-induced psychosis is a relatively rare phenomenon that can occur in otherwise healthy people. Overuse of caffeine may also worsen psychosis in people suffering from schizophrenia.^[1] It is characterized by psychotic symptoms such as delusions, paranoia, and hallucinations.^[2][3] This can happen with ingestion of high doses of caffeine, or when caffeine is chronically abused, but the actual evidence is currently limited.^[1][4][5]

Psychosis is a symptom of psychotic disorders like schizophrenia and severe mood disorders like depression or bipolar disorder. Simply put, psychosis affects the human brain in ways that alter the person's ability to perceive reality. During a psychotic episode, a person may misinterpret and struggle to understand their own thoughts, and additionally "they may have difficulty recognizing what is real and what is not."^[6] In order to spot an individual who could be experiencing Psychosis, look for these symptoms:

1. Schizophrenia: A type of psychotic disorder that impacts how a person experiences reality. Schizophrenia interferes with a person's abilities of cognition, behavior, and emotions. Symptoms of schizophrenia include:
   • Hallucinations- The ability to see or hear something that is not occurring in reality, though to someone with schizophrenia these experiences feel real because it has the "full force and impact of a normal experience."^[7] Most hallucinations that come from schizophrenia consist of hearing things that aren't said, or imagining voices.
   • Delusions- Imagining an event that has falsely occurred or believing something that has not occurred/ is not based in reality.
   • Disorganized thinking and speech- The incapacity to form coherent thoughts, leading to disorganized speech. Disorganized speech is recognized as words put together that do not relate to each other or combine to make any sense logically. Speech in which words are put together meaninglessly in a way that is not able to be understood is commonly referred to as word salad. Disorganized thinking is a common symptom of schizophrenia.
   • Negative Symptoms- The inability to function normally which may include a lack of interest in activities the person has once enjoyed before, experiencing emotions, or participating in normal human routines such as personal hygiene.
2. Bipolar disorder: A type of mood disorder that is typically known for its extreme mood swings and inconsistent behavior patterns. Symptoms of bipolar disorder include:
   • Mania- A main characteristic of bipolar disorder that occurs after a period of severe depression. During this time the person will likely experience: high amounts of energy and happiness, as well as a deep sense of self importance, feeling extremely impulsive/indecisive, making decisions that are potentially risky/harmful, becoming distracted easily, falling into delusions, or thinking illogically.
   • Depression- Another main characteristic of bipolar disorder that occurs before a period of mania. Symptoms of depression include: feeling amounts of deep sadness or irritability, lacking enough energy to function in routine activities, losing interest in activities one has previously enjoyed, suicidal thoughts, an overwhelming sense of worthlessness, difficulty remembering events or focusing, lack of appetite, and illogical thinking.
   • Patterns of mania and depression- Episodes of depression that follow mania or vice versa. During periods of mania and depression, one may actually experience a "normal" mood. Some people can experience:
     • Rapid Cycling: "where a person with bipolar disorder repeatedly swings from a high to a low phase quickly."
     • Mixed State: "where a person with bipolar disorder experiences symptoms of depression and mania together; for example, overactivity with a depressed mood."^[8]
3. General Depression: Also known as major depressive disorder, is a type of mood disorder that negatively impacts a person's mood and ability to function in daily activities.

If a person has any one of these symptoms, they are most likely prone to experience Psychosis.

Consuming excessive amounts of caffeine and combining this with psychotic and mood disorders can impact the severity of the disorders, but excessive consumption can severely affect people who are schizophrenic. 85% of the population of the United States ingests caffeine in some form every day. The most common ways people ingest caffeine is through freshly brewed coffee, instant coffee, tea, soda, and chocolate.

Average caffeine levels are:

• Brewed coffee- 100 mg/6 oz serving
• Instant coffee- 65 mg
• Tea- 40 mg
• Soda- 35 mg
• Chocolate- 5 mg

A majority of the population ingests roughly 210 mg of caffeine every day, while people who have higher tolerances/consume more excessive amounts ingest more than 500 mg of caffeine daily.

80% of people with schizophrenia smoke daily and are heavy smokers. Smoking tends to deplete much of ingested caffeine, so the majority of users with schizophrenia have to consume much more caffeine than others to regulate their caffeine levels.

Many people with schizophrenia use caffeine to combat boredom or to fight the sedating effects of antipsychotic medications. Additionally people with schizophrenia may have polydipsia (causes someone to feel an immense amount of thirst, despite already drinking plenty of hydrating fluids),^[9] so people with this disorder may try to consume more caffeine than normal. A lot of antipsychotic medications contain ingredients that make the mouth more prone to dryness, which would also increase the amount of coffee (containing caffeine) one may uptake.

"Caffeine use can cause restlessness, nervousness, insomnia, rambling speech, and agitation"^[10] worsening the symptoms of schizophrenia. "Caffeine is metabolized by the CYP1A2 enzyme and also acts as a competitive inhibitor of this enzyme. Thus, caffeine can interact with a wide range of psychiatric medications, including antidepressant agents, antipsychotic agents, antimanic agents, antianxiety agents, and sedative agents."^[11] So when caffeine interacts with these specific medications, it can complicate the side effects of the disorder and possibly the medication. To lessen the side effects, people with schizophrenia should consume lower amounts of caffeine.

A consumption of less than 250 mg of caffeine a day has been seen to give better results in better performances on cognitive tasks in people with schizophrenia. Although, more research still needs to be done to determine if the same amount of caffeine that is safe to consume by schizophrenics (> 250 mg/a day) matches up with the general population of people without schizophrenia.^[12]

Chronic caffeine-induced psychosis has been reported in a 47-year-old man with high caffeine intake. The psychosis resolved within seven weeks after lowering caffeine intake, without the use of anti-psychotic medication.^[1]

For schizophrenic people that have an addiction to caffeine, the best way to treat caffeine-induced psychosis is to gradually consume smaller amounts of it over a period of time. Withdrawal to certain drugs may worsen side effects of any psychotic or mood disorders, so it is best for people that have an addiction to slowly drop their levels of caffeine over time instead of completely restricting their consumption of caffeine.

For people who consume excessive amounts of caffeine and don't already have a psychotic disorder, a doctor may prescribe antipsychotics to help stop the effects of psychosis.^[13] For people with a psychotic disorder, it is best to slowly limit caffeine intake and continue taking antipsychotics.