What are amphetamine-type stimulants?
Amphetamine type stimulants (ATS) include amphetamines, methamphetamine, MDMA (ecstasy) and dexamphetamine. They work by increasing levels of serotonin, dopamine and norepinephrine in the brain.
- Serotonin is involved in controlling anger, aggression, body temperature, mood, sleep, sexual feelings, appetite and metabolism.
- Dopamine is involved in behaviour and thought, movement, motivation and reward. It also inhibits prolactin production which is involved in lactation, sleep, mood, attention and learning.
- Norepinephrine is involved in fight-or-flight response and directly increases heart rate and blood pressure, release of glucose from stored energy, and increases blood flow to skeletal muscle.
Effects of amphetamines
Physical effects of amphetamines can include reduced appetite, increased/distorted sensations, hyperactivity, dilated pupils, flushing, restlessness, dry mouth, erectile dysfunction, headache, heart rhythm problems, increased breathing rate, increased blood pressure, fever, sweating, diarrhoea, constipation, blurred vision, impaired speech, dizziness, uncontrollable movements or shaking, insomnia, numbness, palpitations, and arrhythmia. In high doses or chronic use convulsions, dry or itchy skin and acne can occur.
Psychological effects of amphetamines can include anxiety, euphoria, perception of increased energy, repetitive behaviour, feeling of power or superiority, increased aggression, emotional lability and amphetamine psychosis.
Amphetamine psychosis can include delusions, hallucinations and thought disorder. This is thought to be largely due to the increase in dopamine and perhaps serotonin activity caused by amphetamine-like drugs.
Withdrawal from chronic use of amphetamines can include anxiety, depression, agitation, fatigue, excessive sleeping, increased appetite, psychosis and suicidal thoughts.
As well as many of the effects described above, methamphetamine is a particularly damaging and addictive drug and causes additional problems. Methamphetamine users and addicts may lose their teeth abnormally quickly, a condition known as ‘meth mouth’. Methamphetamine causes itchy skin and some users hallucinate that there are insects crawling under their skin. They then scratch and tear at their skin until ugly sores appear.
Users may exhibit sexually compulsive behaviour while under the influence. This puts users at higher risk of sexually transmitted infections (STIs).
While the effects of amphetamines are not directly related to the opiate system, the opiate system and the dopamine system are linked. Therefore increases in dopamine can be limited by blocking the opioid receptors using medications that target the opioid receptors. Research conducted by The Karolinska Institute in Sweden and Fresh Start work supports the use of opiate antagonists in amphetamine patients. The Swedish work involved a trial of oral medication with amphetamine-type drugs and the Fresh Start research investigated long term medications mainly for methamphetamine users.
By using opiate antagonists, the changes in dopamine concentrations that come from using amphetamines can be reduced. By reducing dopamine, the motivation to use amphetamine and the feeling of reward obtained from using is decreased. The result is decreased cravings, decreased desire to use and reduction in the ‘feel’ and ‘like’ of the drug.