The earlier a person starts drinking, the greater the chance he or she will consume more alcohol later in life, according to a new study of humans and rats. People who start drinking during puberty consume more alcohol later in life than those who start drinking later.

Science Daily reports researchers in Germany studied 283 young adults, and asked them when they first started drinking. Their drinking behavior—the number of days they drank, the amount of alcohol they consumed, and whether their drinking was considered hazardous—was assessed at ages 19, 22 and 23. The researchers also studied the effects of early alcohol exposure on drinking patterns later in life in 20 rats.

The researchers found people who had their first drink during puberty had elevated drinking levels compared with those who started drinking at a later age. The animal study found that rats receiving free access to alcohol during puberty consumed more alcohol as adults, compared with animals that first came into contact with alcohol during adulthood.

The results are published in Alcoholism: Clinical & Experimental Research.

In a news release, lead researcher Miriam Schneider explained why the study included both humans and animals. “Adolescents have their first drink at very different ages,” she said. “It would be unethical to make adolescents have their first drink in the course of a study, so this variable requires a longitudinal epidemiological study or experimental animal research to assess drinking behavior.”

She added, “Puberty is a very critical developmental period due to ongoing neurodevelopmental processes in the brain. It is exactly during puberty that substances like drugs of abuse — alcohol, cannabis, etc. — may induce the most destructive and also persistent effects on the still developing brain, which may in some cases even result in neuropsychiatric disorders, such as schizophrenia or addictive disorders.”