Exposing rats to THC increases the likelihood that the animals will later self-administer nicotine. THC-exposed rats are also willing to work harder to obtain nicotine. When extrapolated to people, the findings suggest that THC’s pharmacological impact on the brain may make a person who uses marijuana more vulnerable to developing nicotine addiction, an underappreciated health consequence of marijuana use.
Methamphetamine alters brain structures involved in decision-making and impairs the ability to suppress habitual behaviors that have become useless or counterproductive. The two effects were correlated, indicating that the structural change underlies the decline in mental flexibility.
Ketoprofen, an anti-inflammatory agent commonly prescribed to treat arthritis, reduces neuronal damage in rats that have been exposed to chronic stress and methamphetamine. If this finding of a recent NIDA-supported study extrapolates to humans, anti-inflammatory medications may gain a place in the treatment of methamphetamine addiction.
Researchers have shut down laboratory rats’ compulsive cocaine seeking by stimulating an area of the animals’ prefrontal cortex. The finding raises the possibility that stimulating neurons in this brain area may weaken or break cocaine’s grip on the behavior of people who are addicted to the drug.
A meta-analysis of 13 genome-wide association studies of African Americans’ smoking patterns confirms the significance of genetic variation in region 15q25.1. The analysis also tentatively implicates several genome locations that have not previously been associated with smoking behaviors.
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.
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.
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.