Психотерапия изменяет работу мозга на химическом уровне
August 12, 2008
Nature or Nurture - Are You Who Your Brain Chemistry Says You Are?
A First-of-Its-Kind PET Study Reveals Direct Link Between Hereditary Personality Trait
and Brain's Endorphine System, According to an Article in The Journal of Nuclear Medicine
Reston, Va.—Researchers using positron emission tomography (PET)
have validated a long-held theory that individual personality
traits—particularly reward dependency—are connected to brain chemistry,
a finding that has implications for better understanding and treating
substance abuse and other addictive behaviors.
In a study to identify biochemical correlates of personality traits
in healthy humans, researchers focused their investigation for the
first time on the role of the brain's opioidergic (or endorphine)
system—specifically, the connection between an individual's level of
reward expectancy and the brain's ability to transmit naturally
occurring opiates. The study included 23 males with no history of
substance abuse who were administered Fluoro-ethyl-diprenorphine—a
radiolabeled chemical that binds readily to the brain's naturally
occurring opiate system— and then underwent a PET scan.
The scans were compared to the results of each participant's
Cloninger temperament and character inventory, a questionnaire that
assesses human personality based on four dimensions: novelty seeking,
harm avoidance, reward dependence and persistence. The comparison
revealed that the binding to opiate receptors in the ventral
striatum—an area of the brain known to be a central part of the reward
system—correlated narrowly to the individual degree of reward
dependence. The participants who skewed toward a high need to feel
rewarded by approval were also those with the highest uptake of
opiates, or endorphins, in the reward system. "Our main finding was that reward dependence is the only personality
dimension correlated with opiate receptor binding, and that positive
correlation was restricted to the ventral striatum, which is considered
the key area of the human reward system and of the development of
addictive behavior," said Peter Bartenstein, M.D., professor of nuclear
medicine, Ludwig Maximilians-University, Munich, Germany. "This
correlation means that people with high reward dependence have a high
concentration of opiate receptors available in that area, while people
with low dependence have fewer opiate receptors."
According to the researchers, the biological purpose of the human
reward system is to initiate behavior essential for the maintenance of
the individual—for example, food intake—or the species—for example,
reproduction. Therefore, food or sexual stimuli lead to an
opioid-modulated dopamine release in core structures of the reward
system and subsequently induce the sensation of craving. Modern
addiction research maintains that genetic or acquired abuses of the
reward system are the central basis for the development of addictive
behavior. This latest finding suggests that individuals suffering from
a relative endorphine deficit in their reward system show increased
reward dependence and are probably more at risk for developing
addictions. "This is a novel finding and will provide a deeper understanding of
the functional relation between human personality, neurobiology and
addictive behavior," said Mathias Schreckenberger, M.D., professor of
nuclear medicine, Johannes Gutenberg-University, Mainz, Germany.
"Understanding the central role of neurotransmission processes in
certain brain structures for the expression of psychologically defined
constructs such as personality will make a great difference in the
future of medicine."
The researchers foresee PET becoming the preferred imaging method
for individualized therapy in a range of disorders caused by addictive
behaviour—such as drug abuse or pathological gambling—because it is the
only method able to show specific local changes in different
neurotransmitter systems (opiate, dopamine and serotonine) involved in
addiction. These changes are different in different people and
different types of addiction.
The researchers further suggest that PET could be used to predict a
favorable response to treatment with drugs that block agents such as
morphine, heroin or alcohol from binding to opiate receptors and may
one day aid in determining treatment of other psychiatric diseases,
such as personality disorders. PET may also play a central role in the
development and preclinical evaluation of new anti-craving drugs since
it enables researchers to investigate noninvasively the in vivo
pharmacological effects of these drugs on the reward system.
The group's next study will delve deeper into the description of the
neurochemistry of human personality and expand study sample sizes,
according to Gerhard Gründer, M.D., professor of psychiatry and
psychotherapy, Aachen University, Aachen, Germany. "One of the more interesting aspects of this study," he added, "is
that it shows that PET technology is capable of detecting subtle
biochemical differences in the brain in healthy persons, which may
ultimately be responsible for what we consider the individual
personality. This has far-reaching implications—not only for choosing
the best individual treatments, but also in discussions of an
individual's free will."
Coauthors of "Opiod Receptor PET Reveals the Psycholobiologic
Correlates of Reward Processing" include Mathias Schreckenberger, Peter
Bartenstein, André Klega, Hans-Georg Buchholz, Christina Müller,
department of nuclear medicine, and Armin Scheurich, department of
psychiatry and psychoterapy, all at Johannes Gutenberg-University,
Mainz, Germany; Gerhard Gründer, department of Psychiatry and
Psychotherapy, Aachen University, Aachen, Germany; Ralf Schirrmacher,
Esther Schirrmacher, department of neurology and neurosurgery , McGill
University, Montreal, Canada; Gjermund Henriksen, department of nuclear
medicine, Technical University, Munich, Germany.
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