Psychological distress also appeared more consistently associated with alcohol and tobacco use, whereas autism-related traits were mainly associated with problematic internet use and problematic mobile phone use, according to findings published in PLOS Mental Health. The cross-sectional study does not establish causality or directionality.
Researchers surveyed adults aged 18 to 65 years in Italy from June 2024 to March 2025. Participants were recruited through convenience and snowball sampling, including social media platforms, word of mouth, mailing lists, and flyers at the University of Padova and a university mental health service.
The study assessed autism-related traits using the Autism Spectrum Quotient and psychological distress using the Kessler Psychological Distress Scale, which measures distress over the prior 30 days. Problematic internet use was assessed with the Uso e Abuso di Internet-2 questionnaire, and problematic mobile phone use was assessed with the Mobile Phone Problematic Use Scale for Adults. Alcohol and tobacco use were assessed with the Alcohol, Smoking and Substance Involvement Screening Test.
The Autism Spectrum Quotient was used to measure autism-related traits, not to diagnose autism spectrum disorder. The study used a cutoff of 26 to classify high autism-related traits, while noting that a cutoff of 32 is used in clinical samples. Overall, 61 participants, or 15%, met the lower high-autism-related-trait threshold.
The sample had a mean age of 38 years, and 80% of participants were female. Most participants were Italian, and 63% were originally from Italian islands. Overall, the sample was characterized by low autism-related trait scores, mild psychological distress, normal internet-use scores, and moderate smartphone-use scores.
Age-related differences emerged across several measures. Adults aged 18 to 24 years had the highest mean scores for problematic internet use, problematic mobile phone use, psychological distress, tobacco use, and alcohol use. Scores for problematic internet and mobile phone use declined across older age groups.
Researchers initially conducted the pre-registered multivariate analysis of covariance, comparing participants with low vs high autism-related trait scores while controlling for psychological distress. However, that model had 2 methodological limitations: the low- and high-autism-related-trait groups were imbalanced, with 359 vs 61 participants, and tobacco and alcohol outcomes were zero-inflated, with 51% of participants reporting no tobacco use and 21% reporting no alcohol use.
To address those issues, the researchers also performed multivariate multiple regression using continuous autism-related trait and psychological-distress scores, as well as hurdle models for alcohol and tobacco use.
In the multivariate multiple regression, higher autism-related trait scores and higher psychological-distress scores were both associated with greater problematic internet use. The association was somewhat stronger for psychological distress than for autism-related traits. For problematic internet use, the beta coefficient was 0.74 for psychological distress and 0.59 for autism-related traits.
For problematic mobile phone use, the gap was larger. Psychological distress had a beta coefficient of 0.84, compared with 0.37 for autism-related traits. The researchers reported that psychological distress showed stronger associations with problematic internet use and problematic mobile phone use across the multivariate analyses.
The substance-use findings differed from the digital-use findings. Psychological distress was associated with higher alcohol and tobacco use in the multivariate multiple regression. Autism-related traits were not associated with alcohol use and were inversely associated with tobacco use, making tobacco the main outcome in which autism-related traits and psychological distress diverged in opposite directions.
In hurdle models, autism-related traits were not associated with the probability of being an alcohol or tobacco user, while psychological distress was associated with both alcohol and tobacco use. Among tobacco users, lower autism-related trait scores were associated with greater tobacco-use intensity.
The researchers cautioned that the tobacco finding may not generalize broadly. Among the 61 participants with high autism-related traits, only 1 reported an attention-deficit/hyperactivity disorder diagnosis, 11 reported family history of substance use disorder, and 5 reported family history of behavioral disorders. The researchers wrote that this high-autism-related-trait subgroup “may not represent a population at elevated risk for SUD,” which could partly explain the limited or inverse association between autism-related traits and substance use.
The findings should be interpreted in light of several limitations. The study was cross-sectional, so it cannot determine whether psychological distress contributed to problematic digital use, whether problematic digital use contributed to distress, or whether both reflected other factors. All measures were self-reported, and the study did not include clinical diagnostic assessments for autism spectrum disorder, internet-related disorders, or substance use disorders.
The sample was also nonrepresentative. It was recruited online, predominantly female, and heavily drawn from Italian islands. The researchers noted that living in insular contexts may be associated with social isolation or loneliness, which could affect problematic internet use and limit generalizability.
The study also deviated from its pre-registration. Researchers originally planned to enroll 500 participants and divide them into 5 age groups, but they did not reach that sample size within the planned collection period. Instead, they analyzed 420 participants in 4 quartile-based age groups. A sensitivity analysis treating age as a continuous covariate found that the associations among autism-related traits, psychological distress, and outcomes remained statistically significant.
The researchers wrote that future studies should use longitudinal designs and ecological momentary assessment to clarify the temporal relationships among psychological distress, autism-related traits, problematic internet use, problematic mobile phone use, and substance use. They also suggested that interventions focused on reducing psychological distress and improving coping and emotion-regulation skills may be relevant for people with problematic internet or mobile phone use. They noted that elevated autism-related traits, particularly restricted interests and repetitive behaviors, may also warrant consideration as potential predisposing factors, especially among adolescents.
“Autistic traits and psychological distress were significantly associated with PIU and PMPU, with psychological distress showing stronger associations,” wrote lead study author Matilda Floris, of the University of Padova, and colleagues. The researchers added that problematic internet use and problematic mobile phone use “may be specifically linked to autistic traits, whereas substance use may be more related to psychological distress.”
Disclosures: The study was funded by the National Recovery and Resilience Plan of the European Union (NextGenerationEU). The researchers reported no competing interests.
Source: PLOS Mental Health