A recent comprehensive study by Brazilian researchers has revealed crucial insights into the intergenerational patterns of alcohol and drug use. Analyzing data from 4,280 adolescents and their guardians, the findings underscore that while parental substance use remains a significant risk factor, effective parenting styles can substantially mitigate this influence.
The research, conducted by a team from the Federal University of São Paulo (Unifesp), specifically points to the power of certain educational approaches. These methods can reduce the likelihood of young people engaging in substance use, even in households where parents or caregivers consume substances such as cigarettes, vapes (illegal in Brazil), and cannabis.
The study highlights that family dynamics characterized by strong bonds, parental presence, open dialogue, and clear behavioral rules are particularly effective. These elements are hallmarks of what is known as an “authoritative” parenting style, which masterfully blends warmth and consistent monitoring, creating a protective environment for adolescents.
Authoritative parenting offers key protection
This protective effect is most pronounced with the authoritative parenting style, which demonstrated the greatest capacity to lower youth engagement with alcohol and other drugs. Researchers examined four distinct parenting styles, finding varying degrees of impact on adolescent substance use behaviors.
The “authoritarian” style, characterized by strict rules and less warmth, also showed some risk reduction for drug use, though its impact on alcohol consumption was less significant. Conversely, “permissive” and “neglectful” parenting styles provided no protective benefits, leaving adolescents more vulnerable to substance initiation.
Understanding parental and youth consumption profiles
The study categorized consumption profiles for both parents and adolescents into three groups: abstainers, those who only consume alcohol, and those who use two or more substances. This detailed segmentation allowed for a precise analysis of how parental habits directly correlate with their children’s choices.
Parental alcohol consumption was linked to a 24% probability of their children also using alcoholic beverages and a 6% probability of using two or more drugs. The risks escalate considerably when parents engage in multi-substance use, increasing the likelihood of adolescent alcohol use to 17% and multi-drug use to 28%.
These findings, detailed in an article in the March 2025 edition of “Addictive Behaviors,” emphasize the critical role of parental modeling. Professor Zila Sanchez, lead author from Unifesp’s Department of Preventive Medicine, reinforced the need for parents to acknowledge their influence.
The power of abstention and clear boundaries
Professor Sanchez, coordinator of Unifesp’s Nucleus for Research in Alcohol and Other Drug Use Prevention (Previna), stressed that parental substance use undeniably influences children. “However, if parents establish clear rules and boundaries at home, coupled with affection, these protective factors significantly minimize the risks inherent in their own consumption,” she stated.
The research also identified a powerful predictor of youth abstinence: parental non-use. When parents are abstinent, a striking 89% of adolescents also avoid both alcohol and other licit or illicit drugs. This represented the strongest association found, highlighting the direct impact of parental choices.
A broader perspective on community prevention
This study forms part of a larger initiative funded by Fapesp, focusing on community-based interventions to reduce alcohol consumption among adolescents. The project, titled “Reduction of alcohol consumption among adolescents through a community-based multicomponent intervention,” aims to inform public policies and prevention programs.
Data for this particular article was collected between 2023 and 2024 in four small municipalities in São Paulo state: Cordeirópolis, Iracemápolis, Salesópolis, and Biritiba-Mirim. These diverse settings, with populations ranging from 18,000 to 25,000, provide a rich context for understanding adolescent behaviors.
The needs assessment phase of the project involved all adolescents enrolled in schools within these four municipalities. The average age of the young participants was 14.7 years, with an almost equal distribution between boys and girls. Alcohol consumption in the last month was reported by 19.9% of adolescents, while episodic heavy drinking was reported by 11.4%.
Among parents, the percentages were notably higher, with 56.4% reporting alcohol consumption in the last month and 20.3% engaging in episodic heavy drinking. The researchers utilized advanced statistical techniques, including Latent Class Analysis (LCA) to identify substance use profiles and Latent Transition Analysis (LTA) to model intergenerational associations.
LCA helps uncover unobservable subgroups within a population based on observed response patterns, while LTA assesses the probability of adolescents belonging to specific substance use profiles depending on their parents’ profiles. This robust methodological approach ensures the reliability and depth of the findings.
Normalization of alcohol and long-term health risks
Even within families practicing positive educational methods, the study confirmed that parental alcohol consumption correlates with adolescent use, emphasizing the need for caution regarding the normalization of drinking at home. “When consumption is frequent and treated as trivial, it translates into a greater risk, regardless of the existing emotional bond,” Sanchez noted.
Globally, alcohol stands as a primary risk factor for the rise of non-communicable diseases, including cardiovascular conditions, various cancers, and diabetes. Beyond physical ailments like liver damage and increased susceptibility to infections, alcohol use elevates the risk for anxiety, concentration difficulties, and depressive disorders among young individuals.
Delaying the initiation of substance use among youth is considered one of the most effective strategies for reducing future consumption and associated harms. Epidemiological studies consistently show that community-based interventions—combining school-based prevention, family programs, and environmental strategies—yield the most consistent and long-lasting positive effects.
Despite Brazil’s legal age limit of 18 for alcohol sales, national data reveal a concerning trend. The National Survey on Alcohol and Drugs (Lenad III), released in 2025 by Unifesp in collaboration with the Ministry of Justice, indicates that over half (56%) of the population first experimented with alcohol before turning 18. Furthermore, one-quarter (25.5%) began regular drinking during adolescence.
The Lenad III survey further details that approximately 27.6% of adolescents aged 14 to 17, equivalent to about 3.2 million young people, have consumed alcohol at some point in their lives. In the past year, 19% (2.2 million youths) reported alcohol use. For cannabis, roughly 1 million adolescents have used it at least once, with half doing so in the last year. Across the general population, nearly one in five Brazilians (18.7%) has tried at least one psychoactive substance, excluding alcohol and nicotine products.
