Association between ADHD symptoms, physical effort discounting, and unhealthy lifestyles in adults

Abstract

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental condition marked by difficulties with attention, increased activity levels, and impulsive behaviour, which can impact social, academic, and work-related performance. Its presence in adults is often overlooked and inadequately addressed. Emerging research suggests a link between ADHD and unhealthy lifestyles, including sedentary behaviour, substance use, and effort discounting, a decision-making process where individuals undervalue rewards requiring significant physical or cognitive effort. This study investigates the association between ADHD symptoms, physical effort discounting, and indicators of unhealthy lifestyles in young adults. We recruited 181 participants aged 18-33 years. They completed the Effort-Expenditure for Rewards Task (EEfRT) and a hypothetical effort-discounting task, alongside questionnaires assessing ADHD and developmental co-ordination disorder (DCD) symptoms, physical activity, alcohol, tobacco and drug use. A logistic mixed model was used to analyze effort-discounting decisions, while regression analyses assessed the influence of ADHD symptoms and effort discounting on unhealthy lifestyle indicators. EEfRT decisions were significantly influenced by reward probability, monetary value, and ADHD medication status, whereas choices in the hypothetical effort-discounting task were influenced by money, effort and ADHD symptoms. When exploring the association between all variables, ADHD symptoms were positively correlated with effort discounting in the hypothetical task, smoking, and DCD. Effort discounting was associated with a sedentary lifestyle while smoking correlated with higher BMI and alcohol consumption. Linear and logistic regressions suggested that ADHD symptoms and effort discounting were associated with a sedentary lifestyle, and smoking status was significantly explained by ADHD symptoms. These findings highlight the need for targeted interventions addressing both ADHD symptomatology and lifestyle factors to improve outcomes in affected individuals.

Keywords: Attention; Decision-making; EEfRT; Hyperactivity; Sedentary; Tobacco.

Fig. 1

Effect of predictors on EEfRT decisions after the logistic mixed model. (A) Participants tended to choose the effortful alternative when money increased, but strongly depending on trial probability. Note that effortful choices for low probability trials (12%) were always below 0.5 irrespective of the money at stake, whereas they were above 0.7 in high probability trials, even for small rewards. (B) The effect of fatigue is apparent for all trial types: chances to select the effortful alternative decreased with trial number in all cases. (C) The probability of choosing the effortful alternative with respect to trial probability followed a nearly sigmoid shape for undiagnosed participants and medicated ADHD volunteers. However, the curve was less steep for medicated participants, whose preference for the effortful alternative was higher than the other groups in low-probability trials but similar to them in high-probability trials.

Fig. 2

Effect of money of the effortless alternative and effort level (prospective minutes running) of the effortful alternative on decisions in the hypothetical effort discounting task. For all money amounts, the probability of choosing the high effort alternative was very low when approaching to the maximum effort level. However, as expected, this probability was higher in low effort decisions. In these cases, the money involved in the effortless alternative was the main factor to guide decisions. Note that the money offered in the effortful option was always 20 €. CI, Confidence Interval.

Fig. 3

Scatter plots showing the significant association between effort discounting (k effort) and ADHD symptoms (ASRS-18) (A), ADHD and developmental co-ordination disorder (DCD) symptoms (B), the hypothetical (k effort) and immediate (EEfRT) effort discounting tasks used in this study (C), and hypothetical effort discounting and a sedentary lifestyle (GPAQ) (D). All variables but EEfRT (proportion of effortful choices throughout the task) were transformed as explained in the text. The linear fit prediction with 95% confidence interval is shown for each plot.

Fig. 4

Boxplots illustrating the significant between-group differences in ADHD symptomatology (A, ASRS-18), body-mass index (B, BMI) and alcohol consumption (C, SIAC) for smoker and non-smoker volunteers. Only raw (non-transformed) variables are shown for better interpretability.

Fig. 5

Interaction of ADHD symptoms and effort discounting (hypothetical task) on weekly physical activity (GPAQ). The graph shows that, for participants with low ADHD symptoms (10th percentile), effort discounting was weakly associated with physical activity. However, for participants with high ADHD symptoms (90th percentile), effort discounting strongly predicted a sedentary lifestyle (low GPAQ levels).