“We call this brain response a ‘born to smoke’ pattern,” said study leader Dr. Steven Potkin, professor of psychiatry and human behavior. “Based on these dramatic brain responses to nicotine, if you have hostile, aggressive personality traits, in all likelihood, you have a predisposition to cigarette addiction without ever having even touched a cigarette.” Study results appeared in the January issue of Cognitive Brain Research.
Potkin and Dr. James H. Fallon, professor of anatomy and neurobiology, gave study subjects standard psychiatric personality exams and separated them into two groups — those with high-hostility personality traits, which are marked by anger, aggression and anxiety, and those with low-hostility traits. Both groups included smokers and non-smokers. The groups were given nicotine patches of strengths of 3.5 or 21 milligrams, or placebo, and later subjected to PET scans to see if the nicotine triggered any responses in brain metabolism of glucose energy.
While the PET scans showed no metabolic changes in the low-hostility subjects, nicotine induced dramatic metabolic responses in the high-hostility group individuals in the limbic system and the cortical and subcortical sectors of the brain. Among members of the high-hostility group, smokers showed a metabolic reaction only to the more powerful 21 milligram nicotine patch, while non-smokers reacted to both patches.
The fact that non-smokers in the high-hostility group showed a significant metabolic response to nicotine provides the first biological evidence that people with high-hostility personalities are likely to become dependent on cigarettes because of their brains’ strong response to nicotine, said Potkin. “In turn, this might also help explain why other people have no compelling drive to smoke or can quit smoking with relative ease,” he added.
It is conceivable that a drug that can make a person less hostile and less aggressive could make it easier for that person to quit smoking.
Another speculation: the association between drug use and crime may in part be due to the fact that the kinds of personalities most prone to become drug addicts are more aggressive in the first place. What would be interesting to know is whether people with high levels of hostility who never try drugs or cigarettes are more or less likely to become criminals than those who do. The answer may depend in part on which drug a hostile person becomes addicted to. Some addictive drugs might even have net calming effects that make a hostile and aggressive person less hostile.
Another interesting question: Suppose people with criminal records who smoke who were trying to stop smoking were studied. Would criminals who have a hard time quitting cigarettes who finally manage to quit become more or less likely to commit violent crimes than they were when they were still smoking?
One complication of studying links between nicotine and crime is that nicotine causes brain damage.
Nicotine causes degeneration in one part of the brain, according to professor of psychology Gaylord Ellison, who announced the finding in the journal Neuropharmacology, and at this year's meeting of the Society for Neuroscience.
Ellison found that nicotine causes selective degeneration of the fasciculus retroflexus, the part of the higher brain that primarily controls the dopamine and serotonin levels in the body.
Dopamine controls movement, emotional response, and the ability to experience pleasure and pain, while serotonin regulates a person's mood.
Suppose a person has a brain that is aggressive and hostile and that person becomes a nicotine addict and basically racks up a bunch of brain damage. Then suppose that person manages to quit smoking. Is that person then even more hostile as a result of the brain damage? Or does the type of damage done have the effect of reducing violent behavior? A similar question can be asked about other addictive drugs because lots of addictive drugs cause brain damage.
There is increasing evidence that the fasciculus retroflexus (FR) represents a 'weak link' following the continuous administration of drugs of abuse. A variety of drugs which predominantly potentiate dopamine, including D-amphetamine, methamphetamine, MDMA, cocaine, and cathinone, all induce degeneration in axons from lateral habenula, through the sheath of FR, to midbrain cells such as SN, VTA, and raphe. For some drugs, such as cocaine, this is virtually the only degeneration induced in brain. Continuous nicotine also selectively induces degeneration in FR, but in the other half of the tract, i.e. in axons from medial habenula through the core of the tract to interpeduncular nucleus. This phylogenetically primitive tract carries much of the negative feedback from forebrain back onto midbrain reward cells, and the finding that these descending control pathways are compromised following simulated drug binges has implications for theories of drug addiction but also psychosis in general.
I am a skeptic on the issue of addictive drug legalization because if the barrier to access to addictive brain-damaging substances is lowered then more people will become addicts and damage their brains. What will be the net result? The legalization advocates can't answer that question. It may depend on the drug. Some drugs might damage circuits that cause hostility. Other drugs might damage circuits that suppress hostility. Also, hostility is not the only factor in play here. Impulsiveness, happiness, anxiety, and other aspects of personality may be enhanced or decreased by the sorts of selective brain damage various addictive drugs cause.
|Share |||Randall Parker, 2004 February 14 02:04 PM Brain Addiction|