Table 1.

Summary of core manifestations, prevalence rates, and life-course trajectory of the main neurodevelopmental disorders (NDDs).

NDD	Core Features	Prevalence Rates	Age at Onset	Evolution
Autism spectrum disorder	Qualitative impairment in social communication skills, with stereotyped and restrictive patterns of behavior.	Around 1.5%	Early developmental period	Lifelong; adults with autism spectrum disorder frequently have to face several challenges with respect to co-occurring medical and psychiatric conditions, education, work, and living situations.
Attention-deficit/hyperactivity disorder	Inattention, hyperactivity, and impulsivity.	5%	Before 12 y.o.	Some symptoms may persist into adulthood, although the clinical presentations may change with time and concomitant psychiatric issues may emerge.
Specific learning disorders	Significant deficits in basic writing, reading, or mathematical skills.	5%	Within the first years of elementary school	May improve with early, adequate interventions or may persist into adulthood.
Intellectual disability	Limited cognitive and adaptive functioning.	1–3%	Within the first 3 years of life	Lifelong; frequently associates with psychiatric comorbidities in adult age.
Communication disorders	-Language disorder: difficulties in language acquisition and use, secondary to deficits in language production or comprehension. -Speech sound disorder: Difficulties with speech sound production. -Childhood-onset fluency disorder: Difficulties with speech fluency and time patterning. -Social (pragmatic) communication disorder: Difficulties with social use of language and communication.	-Language disorder: around 10% -Speech sound disorder: around 5% -Childhood-onset fluency disorder: around 1% -Social (Pragmatic) communication disorder: still limited data	Early developmental period	-Language disorder: can improve with early, adequate interventions or may persist into adult life (especially if diagnosed in children ≥4 y.o.); it may have social consequences. -Speech sound disorder: frequently responds well to treatment; it may be lifelong when associated with a language disorder/specific learning disorder. -Childhood-onset fluency disorder: most cases recover from dysfluency; however, it may persist into adulthood. -Social (Pragmatic) communication disorder: variable outcomes; in some cases, difficulties persist into adult life.
Developmental coordination disorder	Difficulties with gross and/or fine motor skills, interfering with daily life activities	5–8% in children ages 5–11 y.o.	Early developmental period	Symptoms may improve; however, coordination difficulties may persist throughout adolescence and adulthood, along with issues in learning new tasks, which may affect professional performance.
Tic disorders	Involuntary, repetitive, sudden twitches, movements, or vocalizations (tics)	1%	Between 2 and 15 y.o. (average around 6 y.o.)	Tic severity improves after adolescence for most patients; tics may persist into adulthood in a relevant minority of subjects who may report low self-esteem, limited peer relationships, high anxiety rates, and poor school or work performance.