New evidence ties ADHD traits to lower activity and higher smoking rates

By Dr. Sanchari Sinha Dutta, Ph.D.May 19 2025

A new study reveals how ADHD symptoms shape motivation, physical activity, and lifestyle choices, suggesting that interventions must address both symptoms and daily habits to improve young adult health outcomes.

Study: Association between ADHD symptoms, physical effort discounting, and unhealthy lifestyles in adults. Image Credit: Inna Kot / Shutterstock

Researchers at the University of Navarra, Spain, investigated the associations between attention-deficit hyperactivity disorder (ADHD) symptoms and lifestyle factors in young adults. The findings are published in the journal Scientific Reports.

Background

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by attentional impairments, increased activity levels, and impulsive behaviors. The condition can affect social, academic, and work-related performance.

The global prevalence of ADHD is 5–7% among children and adolescents. Among adults, the estimated prevalence is 2.6–6.8%; however, the condition often remains under-recognized, under-diagnosed, and poorly treated.

Emerging evidence suggests that ADHD is associated with unhealthy lifestyles and “effort discounting” (a decision-making process where individuals undervalue rewards requiring physical or cognitive effort), even when greater rewards are possible.

In the current study, researchers investigated the associations between ADHD symptoms, physical effort discounting, and unhealthy lifestyle factors, including sedentary behaviour, obesity, and alcohol, tobacco, and drug consumption, among young adults.

Study Design

The study included 181 young adults aged 18 to 33 years. Of all participants, 58 had a current clinical diagnosis of ADHD (30 medicated, 27 non-medicated), and the rest lacked a clinical diagnosis.

For the assessment of physical effort discounting, the participants performed two decision-making tasks: the Effort-Expenditure for Rewards Task (EEfRT), which involves actual effort (e.g., rapid key-pressing for monetary rewards), and a hypothetical effort-discounting task, where participants chose between hypothetical rewards and efforts (e.g., running on a treadmill).

The participants also completed questionnaires assessing ADHD and developmental coordination disorder (DCD) symptoms, physical activity, and substance use.

Study Findings

The study found an association between ADHD symptoms analyzed as a continuum rather than a binary diagnosis, physical effort discounting, and unhealthy lifestyles in young adults.

In the EEfRT, decisions were influenced by reward probability, monetary value, and ADHD medication status. Medicated ADHD participants chose effortful options more often in low-probability trials, suggesting a blunted perception of probability (reduced sensitivity to risk). In the hypothetical task, decisions were tied to money, effort, and ADHD symptoms. Higher ADHD symptoms correlated with greater avoidance of effortful choices.

ADHD symptoms were linked to effort discounting, smoking, and developmental coordination disorder (DCD, a condition affecting motor skills). Effort discounting in the hypothetical task predicted sedentarism, while smoking correlated with higher BMI and alcohol use.

The hypothetical task better captured real-world sedentarism than the EEfRT. Researchers suggest this is because hypothetical efforts (e.g., treadmill running) reflect the subjective cost of effort more closely than lab-based tasks, which may be influenced by immediate monetary rewards.

ADHD and Smoking

ADHD symptoms significantly predicted smoking status. This aligns with prior research suggesting genetic factors, such as impulsivity-related genes, may contribute to both ADHD and smoking. Smoking also correlated with other negative habits, prompting researchers to hypothesize that it may precede other unhealthy behaviors in individuals with ADHD.

Limitations and Future Directions

Due to the limited number of medicated participants, the study could not analyze medication-specific effects. It also did not collect subjective ratings of effort exertion, which could clarify differences between tasks. Future studies should explore causal links between ADHD symptoms, effort processing, and lifestyle habits.

Conclusion

The findings highlight the need for interventions addressing both ADHD symptoms and lifestyle factors. Researchers emphasize holistic strategies targeting effort avoidance and sedentarism to improve long-term outcomes.