Handedness and Attention Deficit/Hyperactivity Disorder Symptoms in College Students

Handedness in ADHD: Meta-Analyses

Meta-analyses have shown that several neurodevelopmental and psychiatric disorders, such as autism spectrum disorder and schizophrenia, are associated with a higher prevalence of atypical (left-, non-right-, or mixed-) handedness. One neurodevelopmental disorder for which this association is unclear is attention deficit hyperactivity disorder (ADHD). Here, some empirical studies have found evidence for a higher prevalence of atypical handedness in individuals with ADHD compared to neurotypical individuals. However, other studies failed to establish such an association. Therefore, meta-analytic integration is critical to estimate whether or not there is an association between handedness and ADHD. We report the results of three meta-analyses (left-, mixed-, and non-right-handedness) comparing handedness in individuals with ADHD to controls (typically developing individuals). The results show evidence of a trend towards elevated levels of atypical handedness when it comes to differences in left- and mixed-handedness (p = 0.09 and p = 0.07, respectively), but do show clear evidence of elevated levels of non-right-handedness between individuals with ADHD and controls (p = 0.02). These findings are discussed in the context of the hypothesis that ADHD is a disorder in which mostly right-hemispheric brain networks are affected. Since right-handedness represents a dominance of the left motor cortex for fine motor behavior, such as writing, as well as a left-hemispheric dominance for language functions, and about 90% of individuals are right-handers, this hypothesis might explain why there is not stronger evidence for an association of left-handedness with ADHD. We suggest that the mechanisms involved in the pathogenesis of ADHD might show an overlap with the mechanisms involved in handedness strength, but not handedness direction.

Cross-lateralisation in children with attention-deficit/hyperactivity disorder and motor skill performance

Cross‐lateralisation and increased motor difficulties have been reported in children with attention‐deficit/hyperactivity disorder (ADHD). Nevertheless, the question of how crossed (i.e. mixed preference) or uncrossed (i.e. same side preference) lateralisation impacts motor performance in children with ADHD has yet to be examined. In this study, previously validated observational measures of hand and foot preference were used to identify right‐handed children with ADHD who display cross‐ (n = 29) and uncross‐lateralisation (n = 31). An uncross‐lateralised typically developing (TD) group (n = 32) was also identified, and included as a control. Motor performance was assessed with seven valid and reliable fine and gross motor tasks performed with both preferred and non‐preferred limbs. Group, task and sex‐related effects were examined. Findings revealed that male (but not female) cross‐lateralised children with ADHD performed significantly worse, respectively, in two of the fine motor tasks (spiral tracing [p < .01], and dot filling [p < .05]). Results suggest that cross‐lateralised hand and foot preference may affect complex motor skills in male children with ADHD. Furthermore, characteristics of ADHD may manifest differently in male and female children. Findings highlight the importance of considering both hand and foot preference when targeting motor interventions for children with ADHD.

Estimated prevalence and associated risk factors of attention deficit hyperactivity disorder (ADHD) among medical college students in a Chinese population

BACKGROUND

To investigate the prevalence of attention deficit hyperactivity disorder (ADHD) among medical college students in a Chinese population.

METHODS

A cross-sectional design was used to collect demographic data on participants and their symptoms of ADHD, anxiety, and depression. Data were collected through questionnaires filled out on a computer or through WeChat, a widely used social media app.

RESULTS

The prevalence of ADHD among 5693 college students was 3.5% (3.02∼3.98%). Individuals with ADHD showed higher scores on scales of anxiety and depression symptoms (both p < 0.05) than the general population. There was a significant difference in the prevalence of ADHD grouped by smoking, drinking, suicidal ideation, suicidal plans, suicidal attempt, anxiety and depression (p < 0.05). The odds ratio (OR) of ADHD was high for suicidal ideation, suicide plans, suicide attempts, anxiety and depression, with ORs of 5.901, 5.46, 6.011, 8.037 and 7.88, respectively. The ORs of suicidal behaviors for ADHD were decreased after adjusting for covariates such as drinking, smoking and depression.

LIMITATIONS

The sample was exclusively selected from three medical-related colleges, which might not be best representation of college students in China. Furthermore, majority of the participants were females.

CONCLUSIONS

ADHD remains a common disorder among Chinese medical college students and is significantly associated with suicidal behaviors, anxiety and depression. It is important to increase awareness and promote effective interventions to this particular population.