Amphetamines constitute a group of synthetic chemical stimulant drugs. They may be inhaled, taken orally or injected. Abuse may result from the consumption as aids to fat-reducing diets or as anti-fatigue agents, or for euphoric effects. Physiological dependence on amphetamine-type drugs develops rapidly and is perpetuated by a strong drive to reach maximum euphoria and excitation. Dependence is psychological rather than physical, but overactivity under the influence of the drug induces exhaustion afterwards which in extreme cases may lead to death. As tolerance to the desired effects develops, intake of the drug must be increased until a level is reached that may exceed the initial dose by several hundred times. A toxic psychosis may occur after weeks of continued use. The amphetamine-induced toxic syndrome is characterized by profound behavioural changes and psychotic episodes with auditory, visual and tactile hallucinations. These may be associate with feelings of panic or aggression and and urge to commit dangerous anti-social acts. High levels of excitations are coupled with the sudden onset of excessive fatigue. The combination of use of amphetamines with that of other drugs such as alcohol or barbiturates can be catastrophic.
Amphetamines been used medically to relieve catarrhal congestion (nasal), as general stimulants, and as slimming agents in cases of obesity. Initially amphetamines produce wakefulness, lessening of fatigue, increased energy and self-confidence and euphoria. This effect is only temporary and as tolerance builds up rapidly, increased dosages are necessary for the same effect. Ultimately these drugs produce restlessness, irritability, anxiety, slurred speech, unsteadiness and dryness of the mouth. They may also result in hallucinations, psychosis, paranoia or schizophrenia. Side-effects include malnutrition. Amphetamine psychosis is often indistinguishable from genuine schizophrenia. The syndrome is the result of direct intoxication by amphetamines and is not an expression of physical dependence.
Recent total numbers of abusers are 2,284,209 for a global rate of 0.5 per 1000. Except for Japan (1.6 per 1000) all countries with extensive abuse are in the Americas: Canada (1.7), Cayman Islands (4.5), Mexico (2.0), Saint Lucia (9.1) and the USA (8.9 per 1000). Moderate abuse countries are in the Americas (Brazil and Bolivia) and Europe (Finland and Sweden). 68 countries and territories report at least some abuse of amphetamines. 86% of the world's abusers are from the USA, and another 9% from Japan. Most of the remaining 5% are from 8 other countries with high and moderate abuse rates.