Study finds largest declines in impulsivity and decreases in alcohol consumption among 18-to-25-year olds

• Impulsivity normally decreases during emerging and young adulthood and is associated with reduced substance abuse.
• Not all individuals, however, "mature out" of impulsive behavior.
• A new study has found that 18-to-25-year olds exhibited the largest declines in impulsivity as well as the sharpest decreases in alcohol consumption.

Personality traits associated with impulsivity normally decrease during emerging and young adulthood, and these decreases are associated with reduced substance use. A new study of "trajectories" of impulsivity and their association with problem alcohol use has found that the 18-to-25-years-of-age group exhibited the largest declines in impulsivity as well as the sharpest decreases in alcohol consumption.

Results will be published in the August 2010 issue of Alcoholism: Clinical & Experimental Research and are currently available at Early View.

"Traits related to impulsivity, such as undirectedness or 'reverse-scored conscientiousness,' tend to normally decrease from late adolescence into early adulthood, approximately from ages 18 to 35," explained Andrew K. Littlefield, a doctoral student in clinical psychology at the University of Missouri and corresponding author for the study.

"This study is unique in examining patterns of impulsive traits across time," added Danielle Dick, assistant professor of psychiatry, psychology, and human and molecular genetics at Virginia Commonwealth University. "It is interesting that the trajectories of impulsivity identified here parallel previous work on trajectories of externalizing behavior - namely, that there is a class of individuals who appear to 'mature out' of impulsive behavior with emerging adulthood, while others do not show this normative maturing out."

"We used a person-centered trajectory approach in order to characterize individual differences in age-related changes in impulsivity," said Littlefield. "This approach allowed us to empirically discover groups of individuals that showed similar stability and change in impulsivity from ages 18 to35."

Littlefield and his colleagues used data drawn from a longitudinal study of individuals at risk for alcohol dependence (AD) because of a family history of alcoholism. Analyses were based on data collected from 489 college students (266 females, 223 males; 51% with a family history of AD) who were first assessed as freshmen at a large, public university and were then assessed six more times during the next 15 years. Initial analyses identified five trajectory groups that differed in baseline levels of impulsivity and developmental patterns of change.

"Our longitudinal trajectory analyses suggested key differences in both initial levels and change in impulsivity from ages 18 to 35," said Littlefield. "Of most importance, our findings suggest that individuals that made the steepest decreases in impulsivity also made the sharpest decreases in alcohol use and alcohol-related problems from ages 18 to 25." The major correlates were alcohol use - typically quantity frequency and a heavy drinking measures - and alcohol problems.

Littlefield said that through identification of distinct trajectory groups, researchers can better understand how different changes in individuals' impulsivity relate to alcohol use and related problems.

"Many researchers and clinicians think of personality as an incredibly stable construct that does not change across time, however, these findings provide clear evidence that at least some individuals undergo significant changes in impulsivity across time," he said. "Future studies could examine why some individuals make significant changes in impulsivity across time whereas other individuals' level of impulsivity remains relatively stable. Identifying factors that enhance or inhibit seemingly beneficial changes in personality may inform treatment approaches that could facilitate decreased impulsivity."