New research suggests that differences in tobacco consumption reflect, in part, differences in the functional efficacy of a specific type of receptor in a pathway of the brain. In animal studies, nicotinic acetylcholine receptors with the α5 subunit played a key role in producing aversive responses to nicotine, thereby dissuading further consumption of the drug.
While viewing images of cigarettes, smokers reported milder cravings when they shifted their focus from the pleasures of smoking to its harmful effects. Brain imaging showed a correlation between the reductions in craving and altered activity levels in regions associated with emotional regulation and reward.
April 2012 New research establishes that benzodiazepines cause addiction in a way similar to that of opioids, cannabinoids, and the club drug GHB. The discovery opens the door to designing new benzodiazepines that counteract anxiety but are not addictive.
Prenatal drug exposure can have behavioral effects that last well into adulthood, according to two studies of adult monkeys prenatally exposed to cocaine. In the first study, drug-exposed monkeys exhibited less flexibility than controls in adjusting to changing circumstances; in the second study, drug-exposed males exhibited a greater preference than controls for having rewards right away, a sign of impulsivity.
NIDA-supported research suggests that glucocorticoid receptor levels during early brain development affect the hard wiring of neural circuits that shape an individual’s basic emotional makeup. In mice, overexpression of the glucocorticoid gene in the first weeks after birth increased anxiety and response to cocaine in adulthood. These findings may help researchers understand the genetic background and the developmental trajectory of addiction.
Nicotine sensitizes the mouse brain to the addictive effects of cocaine, according to recent NIDA-supported research. The results accord with the hypothesis that a person’s initial use of an addictive substance physiologically sensitizes his or her brain to the rewarding and addictive effects of other substances. If the findings carry over to people, then preventing youths from smoking might reduce their vulnerability to cocaine abuse and addiction, and cocaine-dependent individuals might ease their path to recovery by quitting smoking.
New research demonstrated that, in rhesus monkeys, ongoing cocaine exposure weakens two brain functions that people require for successful behavioral change: cognitive flexibility and memory. But the study determined that these changes may not be permanent.