A brain imaging study carried out at Massachusetts General Hospital (MGH) reveals abnormalities in the cortex – the outer surface of the brain – of cocaine addicts that appear to correlate with dysfunction in areas responsible for attention and for reward-based decision-making.
While some of these abnormalities may reflect an inborn vulnerability to drug use, others appear to be the result of long-term cocaine exposure. The report appears in the October 9 issue of Neuron.
"These data point to a mixture of both drug effects and predisposition underlying the structural alterations we observed," says Hans Breiter, MD, principal investigator of the Phenotype Genotype Project in Addiction and Mood Disorder in the MGH Departments of Radiology and Psychiatry. "They also suggest that a key feature of addiction – reduction in the range of activities in which addicts participate – has a neural signature in the form of reduced cortical thickness in frontal regions of the brain."
It is known that addicts make judgments and decisions differently than non-addicted people do. But it is not well understood how these differences relate to structural alterations in the brain – particularly changes in the cortex, the highly folded outer layer that helps plan, execute, and control behavior. Magnetic resonance imaging studies were taken of 20 cocaine addicts and 20 carefully matched control participants to investigate variations in cortical thickness. While the cortical thickness of some brain regions can vary widely among healthy individuals of similar age and background, the total brain volume is usually consistent.
In comparison to their healthy counterparts, cocaine addicts were found to have significantly less overall cortical volume, particularly in areas regulating reward function and involved with decision-making. The marked cortical thinness of areas involved in reward regulation and attention was not compensated by increases in other areas. In addition, although the cortex of some frontal regions is typically thicker in the right hemisphere than the left, this relationship was reversed for the addicts. Throughout the brain, cocaine addicts had much less variation in cortical thickness than did controls.
The participants also took part in several behavioral tests. One test of reward and motivation involves people pressing keyboard keys to control how long they viewed pictures of average and attractive faces. Addicts had much less variation than control participants did in their key pressing to view these faces and overall expressed a lower level of preference to all of the faces, including beautiful female faces toward which most healthy controls have strong positive responses. Those results correlated closely with the reduced cortical thickness in the reward regulation areas of addicts. In tests of the ability to pay careful attention to challenging tasks, the addicts also performed less well than control participants, which also correlated with thinner cortex in another region known to be important for attention.
The decreased variability of cortical thickness and assymetry between hemispheres seen in the addicts was not associated with how long they had been using drugs, Breiter notes, and is likely to reflect an inborn predisposition to drug use. Right- and left-side differences in the brain are important for many behaviors, and when they are altered, there is usually a genetic cause. In contrast, another brain region involved with the regulation of reward – the cingulate – had cortical thickness measures that were related to the length of cocaine exposure but not to how long participants used nicotine or alcohol, implying that cocaine itself caused that difference.
Together, these observations provide evidence that addiction-associated cortical thickness abnormalities may reflect both drug use and a pre-existing inclination to abuse drugs. "The severity of these cortical alterations point to the potential importance of prevention efforts to keep susceptible individuals from beginning to use cocaine," Breiter says. "Next we need to see if these findings are limited to cocaine users by testing larger groups of participants with different addictions and with commonly accompanying diagnoses like depression."
Sue McGreevey | EurekAlert!
Innovative genetic tests for children with developmental disorders and epilepsy
11.07.2018 | Christian-Albrechts-Universität zu Kiel
Oxygen loss in the coastal Baltic Sea is “unprecedentedly severe”
05.07.2018 | European Geosciences Union
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Earth Sciences
19.07.2018 | Power and Electrical Engineering
19.07.2018 | Materials Sciences