Le trouble déficitaire de l’attention/hyperactivité (TDAH) a classiquement une évolution chronique durant l’enfance et un retentissement dans plusieurs secteurs de fonctionnement : famille, école, relations sociales. Son diagnostic repose sur le recueil d’informations concordantes, émanant, si possible, de plusieurs sources. Des fluctuations de la symptomatologie sont cependant rapportées. La plupart sont contexte-dépendantes : l’agitation motrice peut être diminuée ou absente dans un environnement non familier et l’inattention n’est pas toujours apparente en situation d’évaluation. Des variations nycthémérales sont également décrites, avec une accentuation de l’agitation l’après-midi durant le temps scolaire. De plus, le niveau de tolérance de l’entourage peut jouer un rôle dans l’appréciation de l’intensité des symptômes et dans leur retentissement émotionnel. Parmi les syndromes TDAH « partiels », ce sont ceux dont les signes sont principalement identifiés à l’école qui ont une évolution proche des formes classiques. Il importe de connaître ces fluctuations pour ne pas récuser à tort un TDAH sur la foi de l’observation ponctuelle de l’enfant en consultation ou en évaluation psychométrique. L’influence du développement sur l’expression clinique du TDAH complique elle aussi la reconnaissance de ce syndrome à l’adolescence et à l’âge adulte. Une autre cause de variations dans l’expression clinique des symptômes est l’existence d’une comorbidité thymique. Les relations complexes entre manie prépubère et TDAH illustrent bien l’intérêt d’une évaluation attentive du cours temporel de l’agitation/impulsivité et de l’inattention.

Attention-deficit/hyperactivity (ADHD) is a common disorder in school-aged children and is associated with significant impairment in social and academic functioning. Its recognition is based on congruent information from different sources, because most ADHD children and adolescents are not competely aware of impairments caused by inattention and/or hyperactivity/impulsivity. Fluctuations in symptom expression may complicate the diagnosis : during clinical examination or tests sessions, ADHD symptoms may be less severe than usual or completely absent. This review examines variations in ADHD symptoms due to environmental context, internal state, circadian factors, development, psychiatric comorbidity and discusses their clinical relevance. Generally, ADHD symptoms are pervasive and identified in different areas of functioning. Despite their chronicity, they show a relative context-dependency. An unfamiliar environment or situation may lessen symptoms. The same happens in dual relations or in calm settings, when the child receives attention and positive reinforcement from the adult. On the contrary, the classroom situation with its high stimulation level (noise, visual distractors, large class size) is likely to reveal or accentuate instability, impulsivity and inattention. Independently from objective symptom fluctuations, the impact of ADHD symptoms, and their consequences on self-esteem may also vary with the degree of environmental mismatch. Recent research in experimental psychology also draws attention to the motivational state of ADHD children : preference for immediate gratification and delay aversion may explain why most of them show satisfactory attentional capacities in certain activities (for instance video games or TV), while showing impairment in school work or in other effortfull tasks <sup>[4CARLSON CL, TAMM L. Responsiveness of children with attention deficit hyperactivity disorder to reward and response cost : differential impact on response and motivation. J Consult Clin Psychol 2000 ; 68 : 73-83.

Cliccare qui per andare alla sezione Riferimenti]</sup>.The diagnosis of the full ADHD syndrome requires significant impact on functioning in at least two areas. Some children with « situational » ADHD are impaired either in school setting or exclusively at home. Manuzza et al. <sup>[14MANUZZA S, KLEIN RG, BESSLER A et al. Adult psychiatric status of hyperactive boys grown up. Am J Psychiatry 1998 ; 155 : 493-8.

Cliccare qui per andare alla sezione Riferimenti]</sup> report long-term outcome of « situational » versus « pervasive » ADHD. School-ADHD, in opposition to home-ADHD shows similarities with the full blown syndrome, as regards proportion of anti-social personality disorder, psycho-social functioning and academic/professional achievments.Moderate seasonal variations have also been identified with less ADHD symptoms in August <sup>[12KOVALENKO PA, HOVEN CW, WICKS J et al. Seasonal variations in internalizing, externalizing and substance use disorders in youth. Psychiatr Res 2000 ; 94 : 103-19.

Cliccare qui per andare alla sezione Riferimenti]</sup>. This result is likely to reflect a better fit between individual characteristics and environmental demands during school holidays rather than neurobiological changes, as there are no convincing arguments for seasonal fluctuations of serotoninergic tone in ADHD <sup>[18

Cliccare qui per andare alla sezione Riferimenti et

Cliccare qui per andare alla sezione Riferimenti]</sup>. Another cause for variations in ADHD symptom expression may be the co-occurrence of a mood disorder. Relationships between early-onset mania and ADHD are discussed. The appropriate definition of prepubertal mania is still in debate ; its recognition is hindered by symptom overlap and high level of comorbid conditions. Chronic emotional dysregulation with irritability and frequent temper tantrums, sometimes viewed as characteristics of early-onset mania, might reflect a – possibly severe – sub-type of ADHD rather than a prodrome of bipolarity <sup>[9HAZELL PL, CARR V, LEWIN TJ et al. Manic symptoms in young males with ADHD predict functioning but not diagnosis after 6 years. J Am Acad Child Adolesc Psychiatry 2003 ; 42 : 552-60.

Cliccare qui per andare alla sezione Riferimenti]</sup>. A marked cyclicity of symptoms, with periodic accentuation of ADHD and mood symptoms, requires carefull monitoring and systematic analysis of comorbid conditions. Clarification of the complex interrelations between ADHD and bipolar disorder will be obtained from long-term studies.