Posts tagged with dopamine
September 21, 2012 by Cara Flanagan.
In the search to explain why some people become addicted while others don’t, one answer has been that some people have an addictive personality i.e. they are just more likely to become addicted. Support for this idea comes from the phenomenon of ‘addiction transfer’, described in a recent article by Samantha Murphy in the New Scientist (8 September 2012). Addiction transfer refers to the phenomenon that an addict may manage to overcome one addiction but then develops another as a kind of substitute. The addict appears to need to have an addiction. Accidental evidence for addiction transfer comes from studies of people who have undergone weight loss surgery. Overeating can be regarded as a kind of addiction and weight loss surgery cuts obese people off from their original addiction. Researchers estimate that about 15-30% of those who have undergone weight loss surgery transfer to a new addiction.
The explanation outlined in Murphy’s article is that addiction activates the brain reward system and, when this activation stops, the person looks for something else to maintain activity within this reward system. The genetic link in the addiction transfer explanation is that some people are born with lower levels of D2 receptors, resulting in lower levels of dopamine in the reward system. Addiction behaviour has the effect of increasing their dopamine levels, thus explaining why some people are more prone to becoming addicted. Critically this explains why some people, once they have experienced an addiction, need to continue some kind of addictive behaviour if the original one stops.
June 12, 2011 by Cara Flanagan.
One of the explanations for addiction is that some individuals have a biological predisposition because they inherit a particular form of dopamine receptor gene (if you want an explanation of dopamine receptor genes see second paragraph). An interesting link has been made between these genes and evolution. The argument goes that the dispersal of our distant ancestors from Africa was related to riskiness. Individuals with a predisposition to be impulsive and risky rather than careful and reflective would be more likely to explore and find new, desirable environments and would also cope better with new, challenging situations. Recent research has indeed found a link between specific dopamine genes and migration patterns i.e. migrants were more likely to have the version of the dopamine receptor gene that codes for risky behaviour. This shows that the gene has had an adaptive function, and may continue to do so.
Understanding dopamine receptor genes: There are different types of dopamine receptor such as D1R, D2R etc. (D for dopamine, R for receptor and the number denotes the type). The receptor is called D1R and the gene for that receptor is called DRD1, or D2R and DRD2 (which seems confusing to me, but there it is). For any gene there are different forms or allelles. So, for example, we all have a gene for D2R but the form of that gene differs. One person may have the G allele (which is associated with aggression) or the 1A allele (associated with addiction). In the study cited above (Matthews and Butler, 2011) the DRD4 gene was studied and the 7R and 2R versions were associated with risky behaviour whereas the 4R version was linked to being even tempered.
September 26, 2008 by Evie Bentley.
Suppose you had an awful experience, something traumatic which shook you up and upset you deeply. What would the effects of that be? How would you cope? Would you be able to deal with your memories, or would you have flashbacks, panic attacks, feel unable to get on with your life?
Researchers in Germany and the USA have been studying why some people develop PTSD (post-traumatic stress disorder) but others, in the same traumatic circumstances, don’t get the disorder and manage to cope with just bad memories.
The answer appears to be nature, not nurture, and is linked to one of the permissive amines, dopamine. Read the rest of this entry »