TDAH et comorbidités en pédopsychiatrie. Pathologies psychiatriques, affections médicales, troubles de l'apprentissage et de la coordination

ADHD is a common disorder for children and is highly comorbid with a number of psychiatric and somatic disorders, which leads to important social consequences. Therefore, it is important to screen for the presence of other disorders when a diagnosis of ADHD is considered. Because of the associated pathologies, the clinical picture of the ADHD is more complex and represents a diagnostic challenge. Furthermore, the prognostic and the future of children with a comorbid ADHD is much more unfavorable than that of children with ADHD only. It is thus necessary to recognize the presentation of ADHD associated with various and frequently comorbid pathologies knowing that those will change according to age and the developmental stage. The objective of this article is to describe these comorbidities. We are going to discuss pathologies most often associated with ADHD and the impact of its symptomatology on psychiatric disorders, medical affections and other disorders such as learning disorder and developmental coordination disorder. Along these lines, we carried out a mini review of ADHD and comorbidities. Results showed that comorbid psychiatric disorders such as conduct disorders, mood disorders and anxiety are among the most frequently associated with ADHD in clinical practice. Disruptive disorders are the most common comorbidities found with ADHD. Among these disorders, oppositional defiant disorder must be distinguished from conduct disorders. Conduct disorders are highly comorbid with ADHD (in more than a third of the cases) and increase the severity of the clinical picture. When children show at the same time ADHD and a conduct disorder, they are at risk to have an antisocial personality disorder as well as addictive disorders in adulthood. Depressive disorders can be triggered by ADHD since these young patients have to face numerous failures and difficulties in their family, social and school lives. With respect to bipolar disorders, links exist with ADHD. Bipolar disorder and ADHD treatment is complex: both thymoregulators and medication of ADHD are necessary. Finally, anxiety disorders are concomitant in 33 % of ADHD children, an association which deteriorates the symptoms of inattention and distractibility. Furthermore, there is also some overlap between ADHD and addictive behavior, obsessive-compulsive disorder, tics, sleeping disorder and specific learning disorder. There is a high prevalence of the association between ADHD and addictive behaviors in connection with impulsiveness, lack of control, automedication and similarity in the neurobiological circuits. Children with an obsessive-compulsive disorder have ADHD in 33 % of the cases. Although treatments of ADHD and obsessive-compulsive disorder differ, they must be taken simultaneously. It seems that sleeping disorders are not co-occurring with ADHD but intrinsic. Besides, sleeping disorders during childhood can mime an ADHD and complicate the diagnosis to be established, in particular when restless legs syndrome or sleep apnea is present. The comorbidity of ADHD and specific learning disorders is high. Children with specific learning disorders have difficulties staying attentive and their academic performance is often below their full potential, just like the ADHD children. Therefore, clinicians who assess patients for ADHD have to systematically screen for the presence of specific learning disorders and vice versa. Likewise, autistic spectrum disorder and eating disorder are more and more recognized as comorbid entities. The DSM-IV made impossible the concomitance between autism spectrum disorders and ADHD. However, the DSM-5 did recognize the existence of this comorbidity. The association of those two pathologies results in more severe dysfunction for the children, but the treatment of ADHD is going to facilitate the medical care of autism spectrum disorders. ADHD is described as a risk factor for eating disorders. Besides, the co-occurrence of obesity with ADHD is connected to impulsiveness and the tendency to addictive behaviors. Relationships of ADHD with posttraumatic stress disorder and attachment disorder have also been noted. Similarities between ADHD and posttraumatic stress disorder can cause diagnostic errors. Indeed, for both disorders we find the following: agitation, irritability, hypervigilance, sleeping disorders, attention disorders and disorders in the executive functions. Therefore, during the assessment of a child with a clinical picture of ADHD, anamnesis must be completed with the search of traumatic events. On the other hand, attachment disorder can also be confused with ADHD. Difficult temperament can disrupt the process of attachment and is associated with a bigger risk of ADHD. Finally, other medical issues should be considered in the assessment of ADHD: brain injury, epilepsy and obesity for example. ADHD children with a co-occurring condition may be severely impaired and treatment is more complex. ADHD is strongly comorbid with a large number of psychiatric and physical pathologies. It is probably more a set of affections than a homogeneous clinical entity. The longitudinal studies of children with one or several comorbidities showed that the outcome of these children was unfavorable, the association of pathologies causing an important dysfunction. The explanations proposed for this strong tendency of comorbidity with ADHD are that comorbidities have the same risk factors (genetic and environmental) and/or that one of the disorder is a subcategory of another. This leads us to conclude that a better comprehension of the high rates of comorbidities with ADHD is essential to optimize treatment of this condition and prevent some of the negative outcomes associated with comorbid ADHD.