January 16, 2009

High caffeine intake linked to hallucinations

[Posted: Thu 15/01/2009 by Deborah Condon]

People who consume high amounts of caffeine may have a greater tendency to hallucinate, the results of a new study indicate.

Researchers at Durham University in the UK found that those with a higher caffeine intake, from sources such as coffee, tea and caffeinated energy drinks, were more likely to report hallucinatory experiences, such as hearing voices and seeing things that were not there.

The study involved 200 students. All were asked about their typical intake of products containing caffeine. Their proneness to hallucinatory experiences and their stress levels were also assessed.

The researchers found that ‘high caffeine users’ were three times more likely to have heard a person’s voice when there was no one there compared with ‘low caffeine users.

For the purpose of the study, a ‘high caffeine user’ was someone who drank the equivalent of seven cups of instant coffee a day. ‘Low caffeine users’ consumed less than one cup of instant coffee a day.

The researchers suggested that their findings could be due to the fact that caffeine has been found to exacerbate the physiological effects of stress. When under stress, the body releases a stress hormone called cortisol. More of this stress hormone is released in response to stress when people have recently had caffeine.

It is this extra boost of cortisol which may link caffeine intake with an increased tendency to hallucinate, they said.

“Our study shows an association between caffeine intake and hallucination-proneness in students. However, one interpretation may be that those students who were more prone to hallucinations used caffeine to help cope with their experiences. More work is needed to establish whether caffeine consumption, and nutrition in general, has an impact on those kinds of hallucinations that cause distress,” said one of the study’s authors, Dr Charles Fernyhough.

The researchers added that hallucinations are ‘not necessarily a sign of mental illness’.

“Most people will have had brief experiences of hearing voices when there is no one there, and around 3% of people regularly hear such voices. Many of these people cope well with this and live normal lives.”

Details of these findings are published in the academic journal, Personality and Individual Differences.