Posted on 01/22/2002 3:28:01 PM PST by TLBSHOW
WASHINGTON (Reuters) -
Social standing -- being dominant or subordinate -- plays a vital role in determining susceptibility to drug use, scientists said on Tuesday in a study using monkeys that may shed light on human addictions.
Researchers at Wake Forest University in Winston-Salem, North Carolina, found that macaque monkeys deemed to be subordinate in small groups of the animals were much more likely to give themselves doses of cocaine in a laboratory setting than dominant monkeys.
Brain chemistry linked to social rank explains the phenomenon, the scientists said in a study published in the journal Nature Neuroscience.
Where an individual monkey stands on the simian totem pole is reflected in a brain chemical called dopamine, which is intimately linked with cocaine and other types of substance abuse, they found.
The dominant monkeys experienced an increase in a type of dopamine receptor known to be involved in brain pathways for reward processing, and were less vulnerable to cocaine abuse than their wallflower laboratory companions.
Michael Nader, who led the study, said the research demonstrated that environmental changes can have a profound impact on brain chemistry relating to sensitivity to a given addictive drug -- a finding that could have parallels in people.
For example, researchers have pondered why some cocaine users end up as addicts while others do not.
Cocaine acts on the brain by raising levels of dopamine in synapses -- gaps between nerve cells -- with elevated dopamine levels corresponding to the "high" experienced by the user. Dopamine, categorized as a "neurotransmitter," is released during normal nerve impulse transmission in the brain.
Nader and his colleagues studied 20 male monkeys. The animals initially were housed by themselves for a year and a half. The researchers looked at the monkeys' hormonal activity and behavior, then used a sophisticated imaging technique to measure chemical activity in the brain.
NEW ROOMMATES
A change in living arrangements was then imposed. The monkeys were moved into groups of four. In the ensuing social interaction over three months, dominant monkeys emerged in the five groups, and a hierarchy was established.
The researchers then introduced cocaine to the monkeys, allowing them to self-administer doses. The five top monkeys were far less likely to do so than the others.
Brain scans revealed that the dominant monkeys -- those that were the most aggressive and least submissive toward others -- experienced major changes relating to dopamine starting after the group-housing arrangement was imposed.
Because these changes occurred after only three months of group housing and were not seen when the monkeys lived by themselves, the scientists said the changes in brain chemistry resulted from the process of becoming dominant.
"The environmental consequences of those social hierarchies resulted in these changes," Nader said in an interview.
"And the changes were in the dominant animals and not in the subordinate animals. So the positive spin on that is that environmental enrichment can produce rapid changes in the brain that, in this particular case, protected the individual from drug abuse. And that is the applicability (to people)."
Nader said the findings involving these monkeys should not be interpreted to mean that, in people, those at the top of the social ladder are the least susceptible to substance abuse.
"Not so much that every time you get a promotion or you move up in rank, you're less likely to abuse drugs. I don't think it's the social subordination versus the CEO that's the main point. It's that environmental enrichment ... can produce rapid and robust changes in the brain."
Nader also said he envisions the development of drugs that mimic the brain chemistry changes that appear to reduce cocaine susceptibility. But he added that many factors come into play in determining whether a person becomes an addict.
"There are other things going on, for sure," Nader said. "So I shouldn't say that this is the end-all answer to everything. But I think it is a very promising finding."
SKEWED DATA ALERT! Unless these researchers are studying drug use in all-male gangs or prison inmates, the findings are highly suspect. These monkeys do NOT live in all-male groups in the wild.
To the researchers: Before you publish that paper, repeat your study; this time DUPLICATE reality by including females in the study groups. Your results may vary!
Not to mention the added benefit of attentive female monkeys queing off the rolex and benz touting male macaques.
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