Table 2.

Comorbid symptoms or disorders

	Frequency	Treatments
Developmental5
Cognitive; intellectual disability	40–80%	Educational
Language deficits	50–63%	Communication training, speech and language therapy
Attentional problems, impulsivity, or hyperactivity	59%	Behavioural intervention, psychopharmacotherapy (eg, stimulants, atomoxetine, or alpha blockers)
Motor delay	9–19%	Physical therapy
Hypotonia	50%	Physical therapy
Psychiatric22
Anxiety	43–84%	Behavioural treatment such as relaxation, cognitive behavioural treatment, psychopharmacotherapy (eg, SSRIs or alpha-2 agonists)
Depression	2–30%	Psychotherapy, antidepressants
Obsessive compulsive disorder or interfering repetitive behaviour	37%	Behavioural treatment, SSRIs and other drugs such as atypical antipsychotics
Oppositional defiant disorder	7%	Behavioural treatment
Behavioural problems	3%	Behavioural treatment
Behavioural23
Disruptive, irritable, or aggressive behaviour	8–32%	Behavioural intervention, atypical antipsychotics (eg, risperidone or arapiprazole)
Self-injurious behaviour	34%	Behavioural intervention; drugs (eg, risperidone, naltrexone, and others)
Sensory24
Tactile	80–90%	Occupational therapy, behavioural treatment, and desensitisation
Auditory sensitivity	5–47%	Occupational therapy
Neurological25
Seizures and epilepsy	5–49%	Anticonvulsants
Tics	8–10%	Alpha-2 agonists (clonidine and guanfacine) and others such as atomoxetine
Gastrointestinal26
Food selectivity	30–90%	Behavioural treatment, investigation as appropriate for gastrointestinal difficulties
Gastro-oesophageal reflux, constipation	8–59%	Gastrointestinal investigations as appropriate (eg, barium swallow or milk scan for gastrooesophageal reflux; flat plate, clean out, stool softener, or cathartic for constipation as clinically indicated)
Sleep27
Sleep disruption	52–73%	Sleep diary, sleep hygiene, behavioural supports, investigation of possible medical comorbidities as cause, drugs (eg, melatonin and clonidine)

SSRI=selective serotonin reuptake inhibitor.