As a competitive adenosine antagonist, caffeine affects dopamine transmission and has been reported to worsen psychosis in people with schizophrenia and to cause psychosis in otherwise healthy people. We report of case of apparent chronic caffeine-induced psychosis characterized by delusions and paranoia in a 47-year-old man with high caffeine intake. The psychosis resolved within 7 weeks after lowering caffeine intake without use of antipsychotic medication. Clinicians might consider the possibility of caffeinism when evaluating chronic psychosis.
A competitive antagonist of adenosine receptors1 affecting adenosine A1 and A2A receptors2 and, possibly, benzodiazepine receptors,3 as well as an inhibitor of phosphodiesterase and catecholamine metabolism,4 caffeine is readily available from a variety of sources and is widely used by all age groups.5Possibly the most widely used psychoactive drug worldwide,4,6 caffeine use can cause physical dependence.7 In addition to producing stimulant-like effects,8 such as increasing alertness and reducing fatigue4 and increasing motor activity,2 caffeine can cause anxiety,9 agitation, and even aggression.10
The lack of a caffeine-induced psychotic disorder in the Diagnostic and Statistical Manual, Fourth Edition–Text Revision in contrast to other substance-induced psychotic disorders, such as amphetamine,11suggests that it may not be generally accepted that caffeine use should be included in the differential diagnosis of chronic psychosis. Herein, we report a case of presumed caffeinism associated with chronic psychosis that suggests caffeinism might be part of the differential diagnosis of chronic psychosis.
A 47-year-old successful male farmer with no history of psychiatric hospitalization presented with a 7-year history of depression, diminished sleep to as little as 4 hours/night, poor energy, explosive anger, decreased concentration, decreased appetite, anhedonia, and feeling of worthlessness. Seven years before his first presentation, the patient had developed the conviction that people were plotting against him to drive him off of his farm and take his land. At least twice, when he had found dead livestock on his farm, the patient thought that it was part of the plot against him and would entertain no other possibilities. The patient interpreted tire tracks in the driveway as belonging to the car of individuals trying to take his land, even though other more plausible possibilities existed. According to the patient’s wife, the subject interpreted many everyday occurrences as evidence of the plot. Convinced of a plot against him, he installed surveillance cameras in his house and on his farm but never caught anything that would support his conviction that as part of the plot people were coming onto his farm at night. He became so preoccupied with the alleged plot that he neglected the business of the farm and eventually declared bankruptcy as a result. His preoccupation with the plot also led him to neglect the upkeep of his home, and he had his children taken from him because of unsanitary living conditions.
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