2009-01-14 11:50:10
People who drink too much coffee could start seeing ghosts or hearing strange
voices, UK research has suggested.
People who drank more than seven cups of instant coffee a day were three times
more likely to hallucinate than those who took just one, a study found.
A Durham University team questioned 200 students about their caffeine intake,
the journal Personality and Individual Differences reported.
However, academics say the findings do not prove a "causal link".
They also stress that experiencing hallucinations is not a definite sign of
mental illness and that about 3% of people regularly hear voices.
"This is the first step toward looking at the wider factors associated with
hallucinations," said psychology PhD student Simon Jones, who led the study.
Under stress
He said previous research had suggested factors such as childhood trauma could
be linked to hallucinations.
When under stress, the body releases a hormone called cortisol which is
produced in greater quantities after consuming caffeine.
The extra cortisol boost could be what causes a person to hallucinate.
Therefore, Mr James added, it made sense to examine the link between caffeine
and mood.
Besides coffee, sources such as tea, chocolate, "pep" pills and energy drinks
contain caffeine.
After asking the students about their typical intake, the research team
assessed their susceptibility to hallucinatory experiences and stress levels.
Pregnancy problems
Among the experiences reported were seeing things that were not there, hearing
voices, and sensing the presence of dead people.
However, Mr James stressed more work was needed to pin down the link.
He said: "Stressed people may simply drink more caffeine."
And he added: "Even if caffeine were responsible for hallucinations in some
way, the part it plays would be small compared to other factors in life."
The researchers now plan to investigate whether other aspects of diet, such as
sugar and fat consumption, might be associated with hallucinations.
Dr Euan Paul, of the British Coffee Association, stressed the study only
focused on people with a very high caffeine intake.
He also said no details were recorded of other substances consumed that might
have had hallucinogenic effects.
"There are literally thousands of well conducted published studies looking at
all aspects of the coffee, caffeine and health debate and the overall
conclusion clearly demonstrates that moderate caffeine intake, 400-500mg per
day, is safe for the general population and may even confer health benefits."