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Table 1 Summary table

From: Current state of knowledge on the prevalence of neurodevelopmental disorders in childhood according to the DSM-5: a systematic review in accordance with the PRISMA criteria

AuthorYear of publication

Geographical area

Sample

NDDs considered

Sample age

Time window

Differences in sex

Methodology/

type of study

Diagnostic criteria

Sources of information

Type of population

Bosch et al., 2021

Catalonia (Spain):

28 schools

6834 students

All NDDs according to DSM-5: ID, ASD, ADHD, SLD, CDs and MDs

5–17 years

Not specified;

two-phase study, initiated in 2011

Yes, ASD and MD were more common in boys than in girls

Prevalence study

DSM-5

Directly from the child through the administration of specific tests in phase 1; assessment by expert psychiatrists and neuropsychologists in phase 2

School: public

and private. Rural and urban

Bita et al., 2018

LAMIC:

Africa n = 16 (31.4%) (77.6%), Asia–Pacific n = 19 (37.3%), Western Europe n = 7 (13.7%), Latin America n = 7 (13.7%), multisite n = 2 (3.9%)

274,028 subjects

51 studies

ADHD

ASD

Other neurological conditions: epilepsy, hearing impairment, visual impairment, ADHD, behavioural/emotional problems, mental disorders

 < 19 years

Since 1995

Not estimated

Systematic review and meta-analysis

None

Multiple surveys

General (Rural and urban)

Arora et al., 2018

India

(5 regions):

north-central (Palwal), north (Kangra), east (Dhenkanal), west (north Goa) and south (Hyderabad)

3964 children

(83.9% of all invited candidates; 99.4% of all enrolled subjects)

Composition: 2,006 boys and 1,958 girls

NDD: visual impairment, epilepsy, neuromotor impairment including cerebral palsy, hearing impairment, speech and language disorders, ASD and ID

Children from 6 to 9 years old: ADHD and learning disorders

2–9 years

Data were collected between 5 December 2011 and 27 September 2012

No significant difference

Prevalence: 12.4% (95% CI 10.2%-15.0%) in boys versus 10.2% (95% CI 8.4%-12.2%) in girls (p = 0.146)

Prevalence study

DSM-IV-TR

Validated tools for ASD, ADHD and epilepsy (INCLEN Diagnostic Tool)

Cross-sectional survey of children's parents and interviews by accredited professionals, demographic details extracted in the 2011 Indian census

General (rural

and urban)

Carballal et al., 2017

Galicia (Spain)

1286 children

Child and adolescent psychiatric pathology

0–14 years

Between September and November 2015

Not determined

Observational, descriptive and cross-sectional study

DSM-IV-TR

Interview and review of clinical history according to DSM-IV-TR axes

Professional evaluators: 57% school counsellors, 42% child–adolescent mental health unit, 37% public neuropaediatricians, 33.6% schoolteachers, 27.4% speech therapists and 15% early care services

Patients receiving primary mental health services and follow-up

by child–adolescent mental health unit

Wang et al., 2017

China:

East China (20 studies), Central China (10), South China [11], Southwest China (seven), North China (six), Northwest China (five), Northeast China (four) and Hong Kong/Taiwan (four)

275,502 subjects out of

334,000 recruited

67 studies

ADHD

Up to 18 years

30 years

Not determined

Systematic review and meta-analysis

DSM (n = 86.57%)

DSM-III, DSM-III-R, DSM-IV and DSM-5

CCMB-2, CCMB-3,

ICD-9

Clinical interviews were administered in 58.2% (n = 39) of the studies analysed

Medical information was collected from the children (n = 4), teachers and parents in the remaining studies

General

Catalan-Lópet al., 2012

Spain

13,026 subjects

14 studies

ADHD

 < 18 years

Original studies published between January 1980 and August 2011

Male:female ratio of 4:1 in four studies and 2:1 in three studies

Higher prevalence in males

Systematic review and meta-analysis

DSM-III-R, DSM-IV and ICD-10

Symptom-based questionnaires and scales

Parents and teachers

In half of the studies, data collection was divided into 2 stages: (1) psychometric screening and (2) clinical confirmation using standardized diagnostic criteria

General (30%) and school

Pérez Crespo et al., 2019

Catalonia (Spain)

1,326,666 children (51.5% boys and 48.5% girls)

ASD

2–17 years

The most common age range was 6–10 years (48.2%), followed by 2–5 years (30.3%) and 11–17 years (21.5%)

Between 2009 and 2017

4.5 times more common in boys (12,647 boys versus 2,819 girls)

Retrospective analytical cohort study

ICD-9

ICD-9 codes 299.0, 299.1, 299.8, and 299.9

Based on ICD diagnoses in the Catalan Health System

Clinic patients

Kita et al., 2020

Japan

3852 children

NDD: ADHD, ASD, SLD (DD) and coordination disorder

First study to measure comorbidity between them

The prevalence of ODD was also estimated because of its high comorbidity with ADHD

6–9 years

2015 (cross-sectional)

Not calculated

Cross-sectional prevalence study (2015) conducted in schools through parents and teachers, with response rates of 63.9% and 22.5%, respectively

DSM-5

SNAP-IV for ADHD

SRS-2 for ASD

RWC scale for dyslexia (SLD)

Movement Assessment Battery for Kids – Second Edition Checklist (MC) for Motor Disorders

Surveys

Based on parent–teacher rating scale questionnaires

Two evaluators

All rates of agreement on children with suspected NDDs were low (range, 6–16%)

Pupil, community

Fleming et al., 2020

Scotland

766,244 subjects (390,290 [50.9%] boys; 375,954 [49.1%] girls)

ASD

ID

ADHD

Depression

4–19 years

Subjects attended school between 2009 and 2013

Multimorbidity was more common among boys

Girls were less likely than boys to have multimorbidity but experienced a greater adverse impact on educational outcomes

Cross-sectional cohort study

ASD from additional support needs

ADHD if they have received treatment with stimulants or nonstimulants

Depression if they have received antidepressant treatment

Educational and health databases (Scottish Educational Data Exchange Unit (ScotXed) and 2 health databases through ISD (Information Services Division)

Pupil

Hansen et al., 2018

Norway

407 children

Prevalence rates of NDDs (ADHD, TD, ASD) and comorbid disorders

Comorbidity between different NDDs

7–13 years

Between September 2007 and February 2009

Boys constituted a significant majority of referred children (66.3%). There were no significant differences in gender distribution or mean age between the overall NDD group and the psychiatric disorder group without NDDs or between any two specific NDD groups. Among children with ADHD, a significantly higher proportion of girls than boys had comorbid anxiety disorders

Cross-sectional study

DSM-IV

Cross-sectional interviews of parents (at a single timepoint) by experienced doctors

Instruments:

validated diagnoses in children, Schedule for Affective Disorders and Schizophrenia – Present and Lifetime version (Kiddie-SADS-PL), DSM-IV version

Clinical:

Consultation

External

CAMHS

Dalsgaard et al., 2020

Denmark

14.4 million person-years of follow-up

All mental health disorders

Up to 18 years

From 1 January 1995 to December 31, 2015

Anxiety was the most common diagnosis in girls (7.85%)

ADHD was the most common disorder in boys (5.90%). The overall risk of being diagnosed with a mental disorder before 6 years of age was 2.13% overall, with a higher risk in boys (2.79%) than in girls (1.45%)

Cohort study

ICD-10

Classification of Mental and Behavioural disorders: Diagnostic Criteria for Research (ICD-10-DCR), ICD-10

Comprehensive clinical evaluations of all mental disorders by interdisciplinary clinical teams including child and adolescent psychiatrists

Departments in public hospitals

Records in the Health System

Central Registry of Psychiatric Investigations of Denmark and National Registry of Patients of Denmark

Sayal et al.,

2017

Community in general, international studies (USA, UK, Japan, Norway, Ireland, Denmark, Scotland, Sweden, Israel, Netherlands, Germany, Thailand and Australia)

7 systematic reviews

ADHD

Two age groups: children aged

 ≤ 6 years and

adolescents aged up to 18 years transitioning to adult services

Publications between 1996 and 2016

More common in males by a factor of 2–3

Review

DSM-IV

Parent ratings, teacher assessments, or best-estimate diagnostic procedures

Data on pharmacological prescriptions

Primary care

School

Insurance

Private practice

Saito et al.,

2020

Hirosaki, Japan

5016 children were eligible

3954 children completed and returned the screening package

559 children were assessed comprehensively in person

ASD and its comorbidity with other NDDs

5 years

2013–2016

The raw male:female prevalence ratio was 2.2:1

Common comorbid conditions included ADHD (50.6%, male:female = 2.4:1), DCD (63.2% male:female = 2.1:1), ID (36.8%, male:female = 1.7:1), and borderline intellectual functioning (20.7%, male:female = 2.6:1)

Sequential-cross-sectional design study

DSM-5

Autism Spectrum Screening Questionnaire (ASSQ), Strengths and Difficulties Questionnaire (SDQ), ADHD IV Rating Scale (ADHD-RS-IV), Developmental Coordination Disorder Questionnaire (DCDQ), and Parental Stress Index (PSI)

DISC and

ADOS for ASD

WISC-IV

MABC-2: For T. of movement

Comprehensive assessment, which included interviews with children and parents, behavioural observation, and tests of cognitive and motor function. All cases were reviewed by a multidisciplinary research team

HFC Facts

(Hirosaki Five-

year-old Children

Developmental

Health

Check-up)

Shriberg et al.,

2019

USA

346 participants

The objective of this research was to use measurements and analyses in a diagnostic classification system to estimate the prevalence of speech and language disorders in convenience samples of speakers with one of the eight types of complex NDD

Average of 13.3 years

30 years

No sex differences were detected in the prevalence of disorders

Prevalence study

SSD (Speech Sound Disorders)

Audio recordings of speech

Narrow phonetic transcription, prosody–speech coding, and acoustic analysis

Research specialists in the field

Population-

specific

database of participants

recruited for studies of

genetic and

behavioural disorders of speech sound production (i.e., excluding disfluency)

Murphy et al., 2015

Midwestern states,

USA

136 children

Language disability

Preschool language and early literacy skills

One-quarter of children

(21%, n = 29; 1%, n = 2 missing information) had moderate disabilities,

including ASD (n = 13),

ADHD (n = 2), Down syndrome

(n = 2), developmental delay (n = 2), hearing loss

(n = 1) and foetal alcohol syndrome (n = 1)

Average of

56 months (SD = 4.5, range 48–69 months)

Cross-sectional

Not determined

Retrospective prevalence study

No DSM; criteria were specified

Experienced professionals and caregivers

Word recognition task

Pupil population:

children with

language disabilities attending special education schools

Fortes et al., 2015

Low- and middle-income areas of Brazil

1618 children and adolescents

Learning disorders and their comorbidity with other homo- and heterotypic psychiatric disorders

at least 9 years of schooling

Cross-sectional

Yes, learning disorder and ADHD were more prevalent in males than in females

Significant differences in prevalence rates were detected between cities, and several sociodemographic correlates (age, sex, IQ and socioeconomic status) were significantly associated with SLD with global impairment in this sample

Cross-sectional prevalence study

DSM-5

Direct observation by qualified psychologists

Pupil

Faraone et al., 2021

Worldwide

Studies in the analysis included > 2000 participants

ADHD

All ages

20 years

ADHD is more common in men than in women. The meta-analysis examined parents' ratings

of symptoms in 29 studies with more than 42,000 participants, as well as

teacher ratings in 24 studies with more than 56,000 participants; a male:female ratio of 2:1 was found in youth

Systematic review, international consensus of ADHD

We reviewed studies with more than 2000 participants or meta-analyses of five or more studies or

2000 or more participants

DSM

Studies with scientific evidence

General, clinical,

pupil