Researchers at the universities of Leiden, Amsterdam and Granada were the first to investigate the effects of the drug khat on a person's ability to inhibit undesirable behaviour. Frequent use was shown to decrease self-control, with all the potentially dangerous consequences this implies. In view of the increased number of khat users, this is an alarming development.
Research on inhibitory control
The Leiden cognitive psychologist Dr Lorenza Colzato and her colleagues at Leiden University, the University of Amsterdam and the University of Granada asked khat users to carry out a stop-signal task. The subjects were asked to look at a screen and to press the correct button as soon as a green arrow appeared pointing either right or left. If the colour of the arrow immediately changed to red, the subjects were not supposed to press any button. In terms of accuracy and speed of response with the green arrows, khat users performed as well as non-users, but they found it much harder to restrain themselves when the arrow turned red.
On the basis of these results, the researchers conclude that long-term use of khat impacts inhibition, i.e. the ability to repress certain stimuli. This can be dangerous because diminished self-control impacts social and personal functioning. For instance, it leads to more reckless driving and criminal behaviour. The researchers think that it can even play a role in creating addiction: the more someone uses the substance, the less they are able to prevent themselves from using it again.
Increasing number of users
The situation is becoming more alarming due to the fact that the number of khat users has dramatically increased in the last decades, not only in Eastern Africa, where khat has been used for centuries, but also in other regions. As a result of migration, khat is now used in ethnic communities throughout the world. In the Netherlands, khat is included in the Opium Law, and is therefore legal.
Chewing on khat leaves releases juices which have a lightly stimulating effect.
- Bernhard Hommel, Maria Teresa Bajo, Wery P. M. van den Wildenberg, Manuel J. Ruiz, Lorenza S. Colzato. Long-Term Effects of Chronic Khat Use: Impaired Inhibitory Control. Frontiers in Psychology, 2011; 1 DOI: 10.3389/fpsyg.2010.00219
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