Chronic use of the traditional African stimulant 'khat' could contribute to mental-health problems, some observers say.

The BBC reported July 7 that heavy use of the stimulant can lead to insomnia, high blood pressure, and heart problems as well as anxiety, aggression and paranoia. Experts also believe the drug could exacerbate existing mental-health problems among users.

"While I was working as a postman I got depressed and stressed, so I was admitted to hospital, and at the same time I was using khat as well, so they all added up and eventually I ended up mentally ill," said U.K. khat user Abdi Rahman.

Traditional use of khat has given way in some cases to problem use, said Roukiya Omar, a drug-education expert, who said that individuals dealing with unemployment and other issues are "resorting to khat to seek any comfort from the real problems they are having. It's like with any addiction, when people can't handle life they just go and get a drink or go for drugs, so khat is becoming something like that."

Users chew the leaves of the Catha edulis plant; khat is legal in the U.K. but banned in the U.S.

Psychiatrist Eleni Palazidou said she has treated a number of khat users for mental-health problems. "They may have a new episode triggered off by the use of khat or they may get better from an episode of illness and they chew khat and go back to square one," she said. "It's difficult to effectively control their illness, because it stimulates those particular chemical systems in the brain that we are trying to control with the medication."