Technische Universität München

The Entrepreneurial University

Motives of doping use in sports are aimed to achieve physical (e.g. better performance, pain control), psychological (e.g. anxiety, pressure, stress, fatigue) and social (e.g. pressure on result, group acceptance) advantage. This motives are mainly based on human and social behaviours, emotions and personality. The limbic system of the brain controls instinctive behaviour, emotions and motivation.

Neurotransmitters like adrenaline, noradrenaline, dopamine, serotonin and GABA are involved in the control of many emotional and mental states. Most of the psychoactive drugs work by changing either their metabolism, or specific receptor sensitivity to these neurotransmitters. Dopamine receptors are involved in pleasure-seeking behaviour (alcohol and narcotics) as well as in impulsive and aggressive activity. A special group of neurotransmitters (endorphins – enkephalins), structurally similar to opioids, are involved in sensations of pain and pleasure. Dopamine and serotonin influence the “reward system” in the brain. Aversive stimuli activate a “punishment system” which is involved in fight-or-flight response. All drugs that artificially create a dependency increase the amount of dopamine in the reward system. Reward system, participating in seeking pleasure and euphoria constitutes a possible mechanism responsible for taking drugs and addiction. Other reasons for drug abuse is to cope with stress. The learned behaviours can lead to doping use in sports.

Drugs application may cause tolerance, dependency, addiction or withdrawal effects. Tolerance is one of the brain compensating mechanisms that gradually reduce the effects of drugs. Drug dependency is described as a drug intake in order to prevent or diminish the physical or psychological disturbances of withdrawal (abstinence syndrome).

  • Physical dependency occurs when the body is drug deprived. Deprivation leads to physical symptoms such as pain (opiates), severe tremors (alcohol) or convulsions (barbiturates). 
  • Psychological dependency can last much longer than physical dependency. Reward system plays an important role in the development of psychological dependence.

Cocaine and amphetamines are substances with high psychological and low physical dependency. Addiction is a compulsive need of drugs despite of its adverse consequences. The most addictive drugs are opiates, cocaine, amphetamines, alcohol and nicotine acting on reward system in the brain. Estimated risk of dependence development is about

  • 32% for nicotine,
  • 23% for opioids,
  • 15% for alcohol and
  • over 10% for cannabinoids.