Content area
Full Text
PERSPECTIVES
O P I N I O N
The dopamine theory of addiction: 40years of highs and lows
David J.Nutt, Anne Lingford-Hughes, David Erritzoe and Paul R.A.Stokes
Abstract | For several decades, addiction has come to be viewed as a disorder of the dopamine neurotransmitter system; however, this view has not led to new treatments. In this Opinion article, we review the origins of the dopamine theory of addiction and discuss the ability of addictive drugs to elicit the release of dopamine in the human striatum. There is robust evidence that stimulants increase striatal dopamine levels and some evidence that alcohol may have such an effect, but little evidence, if any, that cannabis and opiates increase dopamine levels. Moreover, there is good evidence that striatal dopamine receptor availability and dopamine release are diminished in individuals with stimulant or alcohol dependence but not in individuals with opiate, nicotine or cannabis dependence. These observations have implications for understanding reward and treatment responses in various addictions.
Addiction is one of the biggest health problems facing the world today. Each year, many millions of people die as a result of addiction to substances such as tobacco and alcohol1,
and currently available treatments for addiction have limited efficacy and application. Thus, there is a great need to better understand the brain mechanisms that are involved in addiction so that new, better-targeted interventions can be developed.
A major breakthrough in brain research was made in the 1970s when the potential role of dopamine in addiction was discovered. This breakthrough stemmed from the finding of Olds and Milner2 that rats would willingly and repeatedly self-stimulate particular areas in the brain with electricity, a process that the researchers called positive reinforcement. These areas were subsequently shown to comprise, in part, a set of dopamine neurons3, which explained why drugs that enhanced the actions of this neurotransmitter (for example, stimulants) increased electrical self-stimulation4.
A subsequent series of largely US-based studies revealed that blocking dopamine receptors with neuroleptic drugs impaired the reinforcing effects of stimulants in rats
and primates. This research clearly placed dopamine as the central neurotransmitter in stimulant addiction5 and suggested that it had roles in reward, motivation and incentive behaviour6.
The next conceptual breakthrough came when a group of researchers in Sardinia,...