What is khat? How are its psychiatric effects described in the literature regarding behavioural cha

Fråga: What is khat? How are its psychiatric effects described in the literature regarding behavioural changes and aggression?

Sammanfattning: The leaves of the khat plant are chewed by millions of people mainly in Eastern Africa and in the Arabian Peninsula due to its stimulating effect. The habit of chewing khat is now even observed in western countries because of emigration. The fresh leaves of khat contain, cathinone, a substance which is chemically and pharmacologically similar to amphetamine. Upon wilting of the leaves, cathinone is reduced enzymatically to a less potent compound called cathine.

The main effects of khat observed in habitual chewers are a moderate degree of euphoria, feelings of elation, increased alertness, improved ability to communicate, increased imaginative ability and heightened self-confidence. High doses may induce hyperactivity and manic behaviour. Late effects include weariness, irritability and general apathy.

Svar: Khat (Catha Edulis) is a flowering evergreen tree or large shrub which grows at the high altitudes of Eastern Africa and Southern Arabia. Without pruning, it can reach a height of up to 25 meters. After planted it is ready for harvest after 3 to 5 years. It is then harvested throughout the year. The shoots at the tips of the branches are cut in the early hours of the day, bundled, and then usually wrapped in banana leaves to preserve their moistness and freshness. The material is then speedily transported to the market since it looses its effect upon wilting. In areas where it is grown, khat is known with more than 20 different names of which Qaad or Jaad (Somalia), Mira (Kenya) and Tjaad (Ethiopia) are among them. Formerly, the use of khat was confined to the regions where the plant was grown. However, in recent years the habit of chewing khat has expanded considerably. Today, several million people in Eastern Africa and Arabian peninsula are regular chewers of khat (1). Moreover, because of the large number of refugees from areas where khat is used to western countries during the last 10 years, khat sale and use is frequently being observed in many western countries (1,3).

Of the many alkaloids that have been isolated from the khat leaves, the phenylalkylamine compounds, cathine and cathinone are considered to be responsible for its pharmacological effects. Cathinone is the most potent compound and it is chemically similar to amphetamine, the only difference being a carbonyl group instead of the methylene group in the alpha-position of the amphetamine side chain. The amphetamine-like effects of cathine and cathinone have been shown both in animals and in humans. Rats and monkeys trained to self-administer the drug, took the drug frequently day and night, stopping only upon becoming exhausted and beginning again after recovery. Cathinone is unstable and is quickly transformed by enzymatic reduction to cathine upon wilting of the leaves. Thus, the highest concentrations of cathinone resides in the young newly harvested leaves (1,3). The cathinone content in khat leaves have been shown to vary largely between 0.9 to 3.3 per cent (4).

Khat has been used since antiquity as a recreational and religious drug by natives in Eastern Africa and the Arabian Peninsula. In the traditional social setting, the chewers meet in a house some time late afternoon, usually bringing their own supply of 100 to 200g of khat. The chewers begin to masticate the leaves thoroughly one by one. The juice is swallowed, while the residue of the leaves is stored in the cheek as a bolus of macerated material for further extraction, and is finally ejected. During the session, the group may smoke cigarettes or water-pipes (like in Yemen), and abundant beverages. These sessions may last 3 to 5 hours. In these countries, chewing of khat is socially accepted like the drinking of alcohol in the western culture. In some countries like Yemen, Djibouti and Somalia homes may have special rooms called mufraj, designed for khat sessions. During these sessions, men and rarely women chew khat in congenial social gatherings in which family and friends discuss topics of interest or simply listen to music (1,3,4).

The effects of khat are of course difficult to quantify since the leaves are a non-standardised material the potency of which depends on freshness, origin, and differences in the efficiency of the mastication process among chewers. The main effects of khat observed in habitual chewers are a moderate degree of euphoria, feelings of elation, increased alertness, improved ability to communicate, increased imaginative ability and heightened self-confidence. High doses may induce hyperactivity and, sometimes, manic behaviour. Although there have been several reports of psychosis related to khat chewing largely from western countries, this is rather exceptional in ordinary khat chewers, because of the physical limits to the dose of khat that can be absorbed. Khat is an effective anorectic that diminishes the appetite, and this largely explains the malnutrition often seen in habitual khat users. It also causes hyperthermia and an increase in respiration. Late effects of khat chewing include weariness, irritability, general apathy, sexual disturbance, anorexia, dryness of the mouth, insomnia, and constipation. Long term medical effects of khat chewing include gastritis, oesophagitis or cancer of the oesophagus, and periodontal disease (1,3,4).

In the literature, a total of 17 case reports of khat psychosis is described. The majority of these cases are from western countries. In 1989, Pantelis et al (5) summarised the clinical features of khat induced psychosis in three patients and reviewed further nine cases reported previously. Since then, five new case reports have been described in the literature (6). Most of these cases had similar characteristics. In all cases the psychosis manifested after heavy use of khat; in all but one case the psychotic symptoms rapidly resolved within 1-2 weeks of stopping khat chewing; and treatment with neuroleptics was given in most of them. Nevertheless, the rapid resolution of symptoms was attributed to withdrawal of the substance rather than the treatment. Observers also report that psychotic symptoms tend to recur with renewed intake of khat chewing. The clinical features which dominated included manic symptoms, paranoid delusions, and auditory hallucinations. Among the cases included one case of suicide and one case of a man who killed his wife and a son.

The problems associated with the use of khat confronted the international community already in 1935, when the League of Nations Advisory Committee on the Traffic of Dangerous Drugs discussed the issue in two technical reports (2). Through the UN commission on Narcotic Drugs, international attention was once again directed to the nature and extent of khat use, and in 1971 the Commissions laboratory in Vienna, Austria started investigations on the chemical and pharmacological aspects of khat on behalf of the WHO. These studies made the basis for most of the current scientific data on khat. The conclusion from those studies was that cathinone, in humans causes physical and mental changes typical of amphetamine. On the basis of these data, the UN Commission on Narcotic Drugs has recommended to place cathinone (but not cathine or khat) in Schedule one of the Convention on Psychotropic Substances (1,2). Lately, many countries in Europe and North America have also prohibited the use and sale of khat in their countries, but some others like Great Britain and Holland still tolerate its use.

The mechanism of actions is probable identical to amphetamine as it has the same neurochemical effects in rats on dopamine neurotransmission when systemically or locally applied and the behavioural effects of cathinone in rats are also indistinguishable from amphetamine (Gille-Johnsson and Ståhle, unpublished data).

In the Nordic countries, Norway was the first country to prohibit the use and sale of khat in 1989 followed by Sweden and later by Denmark. In Sweden, according to a decision made by the government 28 September 1989, khat has been classified as a Narcotic. The first court case relating to khat in Sweden took place in Gothenburg in January 1990. The case involved two emigrants who were caught smuggling 14 kg of khat leaves into the country. Both were sentenced to 8 months imprisonment by the District court, but after appeal to the High Court, the sentence was reduced to 4 months (7).