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Nora Volkow in 2009.
Nora Volkow (b. 27 March 1956 Mexico) is director of the National Institute on Drug Abuse (NIDA). She is the great-granddaughter of Russian revolutionary leader and Head of the Fourth International, Leon Trotsky. Her father Esteban Volkov is the son of Leon Trotsky’s elder daughter. Born in Mexico City, Volkow and her three sisters grew up in the house where Trotsky was killed. She attended the Modern American School, then earned a medical degree from National University of Mexico before going to New York University for psychiatric residency. She chose a career in brain research after reading an article on the use of positron emission tomography in studying brain function. She did research at Brookhaven National Laboratory before becoming director of NIDA in 2003. Research
Her imaging studies of the brains of people addicted to drugs have helped to clarify the mechanisms of drug addiction. This research has helped to change the public's view of drug addiction, from that of a moral violation or character flaw to an understanding that pathological changes to brain structure make it very difficult for addicts to give up their addictions. Volkow has shown that abnormalities in the prefrontal cortex of addicts create a feeling of need or craving that addicts know is irrational but cannot prevent. Prefrontal abnormalities also make it difficult to override compulsions to take drugs by exercising cognitive control. The main areas affected are the orbitofrontal cortex, which maintains attention to goals, and the anterior cingulate cortex, that mediates the capacity to monitor and select action plans. Both areas receive stimulation from dopamine centers lower in the brain. A steady influx of dopamine makes it difficult for addicts to shift their attention away from the goal of attaining drugs. It also fastens their attention to the motivational value of drugs, even though these drugs have long stopped providing pleasure. It is now understood that dopamine activation does not signal pleasure. Rather, it signals the importance or relevance of sought-after goals. Addicts have a hard time turning their attention —and their actions— away from the goal of acquiring and consuming drugs. They are caught, she states, in a vicious circle of physical brain changes and the psychological consequences of those changes, leading to further changes. UPDATE - January 16, 2013 – A new study has just been published contesting the interpretation of the large-scale marijuana study I discuss here—that heavy cannabis use begun in the teen years and continued into adulthood brings about declines in IQ scores. Specifically, the new study uses simulation models to suggest that other factors, such as socioeconomic status, may account for the downward IQ trend seen in the Meier et al. study. Indeed, when discussing traits like IQ, it would be surprising for one factor to be 100 percent causal. The strengths of the Meier et al study are that it is longitudinal in nature and that it controlled for a number of factors including years of education, schizophrenia, and other substance abuse. That said, observational studies in humans cannot account for all potentially confounding variables. In contrast, animal studies—though limited in their application to the complex human brain—can more definitively assess the relationship between drug exposure and various outcomes. They have shown that exposure to cannabinoids during adolescent development can cause long-lasting changes in the brain’s reward system as well as the hippocampus, a brain area critical for learning and memory. The message inherent in these and in multiple supporting studies is clear. Regular marijuana use in adolescence is known to be part of a cluster of behaviors that can produce enduring detrimental effects and alter the trajectory of a young person’s life—thwarting his or her...