History and exam

Key diagnostic factors

common

presence of risk factors

Key risk factors include: family history of ADHD, low birth weight, maternal smoking during pregnancy, and male gender.

inability to give close attention to details or making 'careless' mistakes in schoolwork, work, or other activities

DSM-5-TR diagnostic criteria for inattentive presentation.[1]

difficulty sustaining attention in tasks or play activities

DSM-5-TR diagnostic criteria for inattentive presentation.[1]

does not seem to listen when spoken to directly

DSM-5-TR diagnostic criteria for inattentive presentation.[1]

does not follow through on instructions and fails to finish schoolwork, chores, or duties in the workplace

DSM-5-TR diagnostic criteria for inattentive presentation.[1]

often has difficulty organising tasks and activities

DSM-5-TR diagnostic criteria for inattentive presentation.[1]

avoids, dislikes, or is reluctant to engage in tasks that require sustained mental effort (such as schoolwork or homework)

DSM-5-TR diagnostic criteria for inattentive presentation.[1]

often loses things necessary for tasks or activities (e.g., toys, school assignments, pencils, books, or tools)

DSM-5-TR diagnostic criteria for inattentive presentation.[1]

easily distracted by extraneous stimuli

DSM-5-TR diagnostic criteria for inattentive presentation.[1]

forgetful in daily activities

DSM-5-TR diagnostic criteria for inattentive presentation.[1]

fidgets or taps with hands or feet or squirms in seat

DSM-5-TR diagnostic criteria for hyperactive-impulsive presentation (hyperactive symptom).[1]

leaves seat in classroom or in other situations in which remaining seated is expected

DSM-5-TR diagnostic criteria for hyperactive-impulsive presentation (hyperactive symptom).[1]

runs about or climbs excessively during inappropriate situations

DSM-5-TR diagnostic criteria for hyperactive-impulsive presentation (hyperactive symptom).[1]

difficulty playing or engaging in leisure activities quietly

DSM-5-TR diagnostic criteria for hyperactive-impulsive presentation (hyperactive symptom).[1]

often 'on the go' or acts as if 'driven by a motor'

DSM-5-TR diagnostic criteria for hyperactive-impulsive presentation (hyperactive symptom).[1]

often talks excessively

DSM-5-TR diagnostic criteria for hyperactive-impulsive presentation (hyperactive symptom).[1]

often blurts out answers before questions have been completed

DSM-5-TR diagnostic criteria for hyperactive-impulsive presentation (impulsive symptom).[1]

often has difficulty awaiting turn

DSM-5-TR diagnostic criteria for hyperactive-impulsive presentation (impulsive symptom).[1]

often interrupts or intrudes on others (e.g., butts into conversations or games)

DSM-5-TR diagnostic criteria for hyperactive-impulsive presentation (impulsive symptom).[1]

Other diagnostic factors

common

mild mood symptoms (dysphoria, mood lability, irritability, boredom)

May be an associated symptom.[32]

anxiety

May be an associated symptom.[92]

difficulty with peer interactions

May be an associated symptom.[32][98]

low self-esteem

May be an associated symptom, probably related to academic, peer, and personal failures.[32] Children with ADHD are often corrected by teachers and parents multiple times throughout the day, affirming their sense of low self-esteem.

working memory (i.e., short-term memory) impairment

Associated sign on neuropsychological testing.[95]

processing speed impairment (i.e., the rate at which information is dealt with)

Associated sign on neuropsychological testing.[96]

Risk factors

strong

family history of ADHD

There is substantial evidence for a genetic predisposition for ADHD, with the mean heritability for ADHD shown to be 76% based on twin studies.[30]

male sex

Community studies such as the National Survey of Children's Health show male-to-female prevalence rates of around 2.1 to 1.0, while in clinic populations the ratio has been shown to be as high as 10 to 1.[14]​​[17] However, ADHD may be under-recognised and underdiagnosed in girls.[18]

low birth weight

Family studies suggest a causal role for low birth weight in the development of ADHD.[40]​ Although children with extremely low birth weight (<1000 g) form only a small percentage of all children with ADHD, studies have found that extremely low birth weight children have 3 times the risk of developing ADHD.[73] Low birth weight (<2500 g) is also a risk factor for ADHD.[38][74]

epilepsy

Children with epilepsy are at increased risk for cognitive and behavioural disorders including ADHD. While the reported prevalence rates vary depending on study population and methods, clinical-based studies commonly report ADHD in 25% to 40% of children with epilepsy.[24] While there can be contributions from persistent seizures and/or medication, one large study of childhood absence epilepsy found that 36% of the newly diagnosed cohort exhibited attention deficits despite otherwise intact neurocognitive functioning.[75]

tic disorders

The co-occurence of tic disorders and dyspraxia (developmental co-ordination disorder) are increased in children with ADHD.[1]

weak

maternal nicotine use during pregnancy

A Finnish study showed a dose-response relationship between nicotine exposure during pregnancy (maternal cotinine levels) and prevalence of offspring ADHD.[39]​ A study of 356 British children with ADHD found that maternal smoking during pregnancy increased the risk of hyperactive-impulsive symptoms but not inattentive symptoms.[22] It is considered likely that this association is due to genetic confounding.[46]

maternal paracetamol use during pregnancy

Long-term maternal use of paracetamol in pregnancy has been associated with an increased likelihood of neurodevelopmental conditions including ADHD in children, although it is possible that this association may be due in part or in full to unmeasured familial confounding factors.[76][77]​ One cohort study found that cord biomarkers of fetal exposure to paracetamol were associated with significantly increased risk of childhood ADHD and ASD in a dose-response fashion, although further evidence is required regarding potential causality.[78]

obstetric complications in pregnancy or labour

Pregnancy and delivery complications such as toxaemia, eclampsia, poor maternal health, maternal increasing age, fetal postmaturity, duration of labour, fetal distress, low birth weight, and antepartum haemorrhage appear to confer a predisposition for ADHD.[10]

gestational exposure to stress

A prospective study of 290 first-time Scandinavian mothers found gestational exposure to stress correlated with ADHD in offspring at 7 years of age.[43]

psychosocial adversity

Rutter's study of families in the Isle of Wight yielded 6 risk factors that correlated with childhood mental disturbance, and a positive association between Rutter's index of adversity and ADHD has been demonstrated.[79][80][81]​ These factors include severe marital discord, low social class, large family size, paternal criminal justice system involvement, maternal mental disorder, and foster placement. Another study found that lower social class increased risk of hyperactive-impulsive symptoms but not inattentive symptoms.[22]

lead exposure

A dose-response relationship between lead exposure and ADHD has been demonstrated.[44][82]​​

traumatic brain injury

More-severe brain injury is correlated with a greater change in ADHD symptoms.[83][84]

severe early deprivation

Severe early deprivation (such as institutional rearing or child maltreatment) has been shown to contribute to ADHD.[48]

iron deficiency

Several studies have suggested iron deficiency (and/or low ferritin levels) may be a risk factor in the development of ADHD.[41][85][86]

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