Trouble déficitaire de l'attention/hyperactivité

ADHD is characterized by three core symptoms: inattention, hyperactivity, and impulsivity. Inattention includes distractibility, difficulty sustaining focus, and forgetfulness. Hyperactivity involves constant movement and fidgeting. Impulsivity involves acting without planning or thinking, including difficulty delaying gratification. These symptoms must manifest before age 12 and be evident across multiple settings for diagnosis.

Neuroimaging reveals reduced activity in the prefrontal cortex with reduced cortical thickness in individuals with ADHD, areas critical for planning and behavior control. The delayed maturation hypothesis suggests slower brain development, particularly in the prefrontal cortex, leading to weaker neural connections. Dysregulation of dopamine, acetylcholine, and melatonin further impacts reward motivation and impulse control, underlying many ADHD symptoms.

Risk factors include genetic predisposition, premature birth, low birth weight, prenatal alcohol or smoking exposure, childhood trauma, poverty, and lead or pesticide exposure. Genetic factors account for up to 70% of ADHD variance, involving multiple genes linked to dopamine and serotonin regulation. Environmental factors such as prenatal nicotine exposure and childhood adversity further elevate risk.

Boys are 2 to 4 times more likely than girls to develop ADHD. The reasons for this gender difference involve both biological and diagnostic factors. Boys may display more overt hyperactivity and impulsivity symptoms, making ADHD more noticeable to parents and educators, whereas girls may exhibit inattention more subtly, leading to underdiagnosis.

Untreated individuals diagnosed in childhood often experience lower educational attainment, higher unemployment rates, poorer social functioning, and increased risk of substance abuse. ADHD correlates with impulsive decision-making, contributing to higher rates of traffic accidents and legal troubles. Among those diagnosed, 30% to 80% continue to experience symptoms into adulthood, affecting occupational success and social interactions.

Cognitive theories link deficits in executive functioning, like poor working memory and emotion regulation, to academic challenges in ADHD. These neurobiological differences affect planning, impulse control, and reward processing. Children with ADHD may struggle to complete schoolwork, disrupt classroom settings, and face rejection from peers due to impulsive or socially intrusive behavior resulting from weak executive control.

Treatment options include behavioral therapy, educational support, and medications like methylphenidate or amphetamine salts, which enhance dopamine activity. Early intervention and consistent treatment significantly improve outcomes, reducing the likelihood of academic failure, social isolation, and substance use disorders. Research continues to refine understanding and treatment strategies, offering hope for better management and improved quality of life.