Louis Lewin published his influential classification in 1924, distinguishing between stimulants (nicotine; caffeine-containing compounds such as coffee, tea, mate); inebriants (alcohol, ether); hallucinogens (lysergic acid diethylamide [LSD], peyote); euphoriants (cocaine; opium derivatives such as morphine, codeine, heroin); and hypnotics. Also, animal BLZ945 research and functional brain imaging studies in humans have led to the current influential hypothesis that all drugs

of abuse share a common property in exerting their addictive and reinforcing Inhibitors,research,lifescience,medical effects by (i) acting on the brain’s reward system and (ii) conditioning the brain by causing it to interpret drug signals as biologically rewarding or potentially Inhibitors,research,lifescience,medical salient stimuli comparable to food or sex. Cues associated with morphine, nicotine, or cocaine activate specific cortical and limbic brain regions. This conditioning involves the prefrontal cortex and glutamate systems. However, in rats, this pattern of activation displays similarities to that elicited by conditioning to a natural reward-highly palatable food such as chocolate.21 Confronted Inhibitors,research,lifescience,medical by cues that serve as drug reminders, the individual experiences craving, and the degree of voluntary control that he or she is able to exert may be impaired. This hypothesis is partly derived from Pavlov’s conditioning paradigm, where food is equated to cocaine, the animal’s salivation

Inhibitors,research,lifescience,medical to cocaine craving, and the bell to the drug cue.22 Family, adoption, and twin studies have demonstrated the intervention of genetic factors in addiction,23 notably in alcohol abuse and dependence. Genetic factors interact in a complex way with the environment.24-26 Addiction – history of a word The definition of addiction has evolved over time. Today, addiction is defined by Inhibitors,research,lifescience,medical the characteristic features that are shared by a variety of substances: (1) the pattern of administration can progress from use, to abuse, to dependence and (ii), as discussed in the previous paragraph, a common feature of several substances is that they induce pleasure by activating a mesolimbic dopaminergic

reward system, and dependence by mechanisms involving adaptation of prefrontal glutamatergic innervation to the nucleus accumbens. The term “addiction,” in its current medical meaning, was used first in English-speaking countries, and then passed on to other languages that had used Cell Host & Microbe other terms previously. For instance, addiction has displaced the words toxicomanie or assuétude in French. Interestingly, the word assuétude (from the Latin assuetudo [habit]) had originally been introduced into French in 1885 to translate the English addiction.27 German uses non-Latin roots, such as Abhängigkeit (dependence), Sucht (addiction), and Rausch (intoxication). In Roman law and in the Middle Ages, addiction was the sentence pronounced against an insolvent debtor who was given over to a master to repay his debts with his work.