Comorbidités et diagnostics différentiels du Trouble Déficit de l’Attention Hyperactivité (TDAH) en fonction de l’âge

Attention Deficit Hyperactivity Disorder (ADHD) is associated with neurodevelopmental and psychiatric comorbidities throughout life, with a profile of co-occurring disorders that tend to become more complex over time. This article synthesizes the main comorbidities and differential diagnoses of ADHD to provide guidance and facilitate the diagnostic and therapeutic process. In adolescents and adults, it is common for ADHD symptoms to be difficult to spot amid substance abuse disorders or mood disorders. However, diagnosing ADHD is crucial because its treatment can decisively improve social functioning and prognosis for individuals with comorbidities. Most comorbid disorders also serve as differential diagnoses for ADHD, with several symptoms that can be shared across multiple diagnostic categories. This is the case with difficulties in concentration, impulsivity, and irritability, for example. Comorbidities of ADHD in children and adolescents include neurodevelopmental disorders such as autism spectrum disorder (ASD), intellectual developmental disorder (IDD), communication disorders, specific learning disorders, and motor development disorders. A meta-analysis found a lifetime prevalence of ADHD in ASD to be 40,2%, and in children with ADHD, a co-occurrent diagnosis of ASD is found in 20 to 30% [1], [2]. The diagnostic process can be delayed in people with both ADHD and ASD. While treatment of ADHD has documented efficacy in this population, a slow titration is recommended to minimise the risk of side effects [3]. The prevalence of ADHD in children with Intellectual Disability is 39%, with higher figures in syndromic conditions such as fragile X [4]. Externalizing disorders such as oppositional defiant disorder (ODD) and conduct disorder (CD) associated with ADHD strongly influence psychosocial functioning and prognosis. Oppositional defiant disorder (ODD) is frequent in children and adolescents with ADHD, about 40 to 60% in clinical samples and 20 to 30% in the general population. Internalizing and stress-related disorders are also frequent in persons with ADHD at different ages. The presence of ADHD increases the risk of being exposed to accidents and other potentially traumatising life events. ADHD is a risk factor for post-traumatic stress disorder, with rates four times higher compared with controls [5]. Anxiety disorders can begin at a young age with separation anxiety disorder or generalised anxiety disorder and affect about 50% adults with ADHD [6]. In adults with ADHD, depressive disorders are 3 to 5 times more likely than in controls [7]. The association between a mood disorder and impulsivity increases the risk of suicidal behaviours [8]. Bipolar disorder is found in 15% of adults with ADHD and is likely to be associated with an early onset, a more severe course and substance use disorder [9]. Personality disorders are also prevalent conditions in adults with ADHD with a prevalence of 20%. Maladaptive personality traits are often preceded by externalising symptoms during adolescence. Borderline personality disorder is more frequent in females, whereas males with ADHD more often present with narcissistic or antisocial personality disorders [10]. Clinical analysis of comorbidities and differential diagnoses of ADHD requires a precise developmental history. Cross-referencing data from multiple informants and conducting semi-structured interviews are typically valuable aids for clinicians. Establishing therapeutic strategies for ADHD with one or more comorbidities requires determining which disorder is most debilitating. Therefore, the therapeutic project proceeds in stages with successive reassessments. In summary, ADHD is often accompanied by various neurodevelopmental and psychiatric comorbidities, which can complicate diagnosis and treatment. A thorough clinical evaluation, including developmental history, cross-referencing of information, and consideration of differential diagnoses, is essential for accurate diagnosis and effective management of ADHD and its comorbidities.