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Arch Iran Med. October 2019;22(10):546-553
Original Article
Prevalence of Autism and its Comorbidities and the
Relationship with Maternal Psychopathology: A National
Population-Based Study
Mohammad Reza Mohammadi, MD1; Nastaran Ahmadi, PhD2; Ali Khaleghi, PhD1; Hadi Zarafshan, PhD1*; Seyed-Ali Mostafavi, PhD1;
Koorosh Kamali, PhD3; Mehdi Rahgozar, PhD4; Ameneh Ahmadi, MSc1; Zahra Hooshyari, PhD1; Seyyed Salman Alavi, PhD1; Alia Shakiba,
MD1; Maryam Salmanian1; Parviz Molavi, MD5; Nasrin Sarraf, MD6; Seyed Kaveh Hojjat, MD7; Soleiman Mohammadzadeh, MD8; Shahrokh
Amiri, MD9; Soroor Arman, MD10; Ahmad Ghanizadeh11
1Psychiatry and Psychology Research Center, Tehran University of Medical Sciences, Tehran, Iran
2Yazd Cardiovascular Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
3Department of Public Health, School of Public Health, Zanjan University of Medical Sciences, Zanjan, Iran
4Department of Biostatistics, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
5Department of Psychiatry, Fatemi Hospital, Ardabil University of Medical Science, Ardabil, Iran
6Department of Child and Adolescent psychiatry, School of Medicine, Qazvin University of Medical Sciences, Qazvin, Iran
7Addiction and Behavioral Sciences Research center, North Khorasan University of Medical Sciences, Bojnurd, Iran
8Department of Psychiatry, Neuroscience Research Center, Kurdistan University of Medical Sciences, Sanandaj, Iran
9Research Center of Psychiatry and Behavioral Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
10Behavioral Sciences Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
11Department of Psychiatry, Hafez Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
Received: December 30, 2018, Accepted: September 8, 2019, ePublished: October 1, 2019
Abstract
Background: There is no clear picture regarding the prevalence rates of autism and its comorbidities among Iranian children and
adolescents. The present study aimed to estimate these rates as part of a large national population-based study on epidemiology of
psychiatric disorders in Iranian children and adolescents.
Methods: The total sample consisted of 31 000 children and adolescents between 6 to 18 years of age. The Kiddie Schedule for
Affective Disorders and Schizophrenia for School-Age Present and Life time version (K-SADS-PL) was used as the diagnostic tool.
Results: The prevalence of autism in the total sample is equal to 0.1% (10 per 10 000), with a 2:1 male-to-female ratio. In total,
86% of people with autism had at least one comorbid condition. Intellectual disability, epilepsy, enuresis and attention deficit and
hyperactivity disorder (ADHD) with prevalence rates of 70.3%, 29.7%, 27% and 21.62%, respectively, were the most prevalent
comorbid conditions in people with autism. Maternal personality disorders were also shown to be associated with increasing risk
of autism.
Conclusion: The present study shows high prevalence rates for autism and its comorbid conditions among Iranian children and
adolescents. It also reveals that there is a relationship between some maternal psychiatric disorders and the risk of autism.
Keywords: Autism, Attention deficit-hyperactivity disorder, Comorbidity, Epilepsy, Intellectual disability, Prevalence
Cite this article as: Mohammadi MR, Ahmadi N, Khaleghi A, Zarafshan H, Mostafavi SA, Kamali K, et al. Prevalence of autism
and its comorbidities and the relationship with maternal psychopathology: a national population-based study. Arch Iran Med.
2019;22(10):546–553.
*Corresponding Author: Hadi Zarafshan, PhD; Department of Autism and Neurodevelopmental Disorders, Psychiatry and Psychology Research Center, Roozbeh
Hospital, Tehran University of Medical Sciences, Tehran, Iran. Tel: +989127967889, Fax: +98-21-55421959, Email: zarafshan84@gmail.com.
www.aimjournal.ir
http
ARCHIVES OF
IRANIAN
MEDICINE
Introduction
Autism spectrum disorder (ASD) is a severe
neurodevelopmental disorder characterized by deficits in
social and communication skills as well as restricted and
repetitive behaviors.1 Its prevalence has risen dramatically
in recent years; for example, its prevalence in the United
States was reported at 0.67% in 2000, 1.47% in 2010 and
2.58% in 2016.2 Some researchers argue that improvement
in diagnostic methods and changes in definition have
contributed to this rise to some extent. Most rigorous
studies to determine the prevalence of ASD have been
conducted in developed countries. In Iran, as a low and
middle-income country, the prevalence rate of autism
has been investigated in only few studies. The first study
was published in 2008. In this school-based study, 2000
school-aged children were randomly selected from typical
schools in Shiraz. A parent report rating scale based on the
Diagnostic and Statistical Manual of Mental Disorders-
IV-TR (DSM-IV-TR) criteria of pervasive developmental
disorders (PDD) symptoms was used. The results showed
that about 1.9% and 0.5% of the sample were screened
positive for probable autistic disorder and probable
Open
Access
Arch Iran Med, Volume 22, Issue 10, October 2019 547
Prevalence, Comorbidities and Maternal Psychopathology of ASD
Asperger’s disorder, respectively.3 In another study, the
obtained data from the Iranian national screening program
for special needs was explored to estimate the prevalence of
autism among five-year-old children. This study showed
the prevalence of typical autism at 6.26 per 10 000. The
results of this study were limited to only five-year-old
children and typical autism.4
Comorbid psychiatric and medical conditions
are common in people with ASD and make it more
complicated to manage5-8 and drastically influence the
progress and outcomes of this disorder.9 Structured
diagnostic interviews have shown that more than 70% of
children with ASD have at least one comorbid disorder.10
Intellectual disability, epilepsy and ADHD are the most
common comorbidities in people with ASD.11 It has
been reported that age and sex have some impact on the
prevalence rate of comorbidities; ADHD is more common
among males11 and epilepsy is more common among
females.12,13 Also, it has been reported that the prevalence
of schizophrenia increased with age.
In Iran, there is only one published study on comorbid
conditions among children with autism. This study had a
small sample size (n = 91) and only included children from
five special schools for autistic students located in Tehran,
the capital of Iran.14 Nevertheless, this study showed that
72% of participants had at least one comorbid condition,
and attention‐deficit/hyperactivity disorder and epileptic
disorders were the most prevalent comorbid conditions
among students with autism.
Also, it has been shown that the relatives of people
with autism, especially their parents, are at higher risk of
experiencing psychiatric disorders.15,16 For example, studies
using semi-structured psychiatric interviews reveal that 20
to 37% of the relatives of people with autism have had a life
time history of major depression.17 A recent population-
based study also showed that psychiatric disorders are more
common in parents of children with autism; higher risk of
autism among children was associated with diagnosis of
schizophrenia in both parents, depression in mothers, and
neurotic and personality disorder and other nonpsychotic
disorders.18 Most researchers believe that this association
means that there are common genetic/familial factors
between autism and other psychiatric disorders and also
that genetic factors underlie autism.16
In the current study, using data retrieved from a large-
sample population-based study,19 we aimed to estimate
the prevalence of autism, its comorbidities and the role of
parental psychiatric disorders in increased risk of autism
among Iranian children and adolescents.
Materials and Methods
Participants and Sampling
This study is part of a large-sample national population-
based study on the epidemiology of psychiatric disorders
among Iranian children and adolescents. It was a cross-
sectional study on children and adolescents aged 6 to
18 years and was implemented in all provinces of Iran.
Assuming a prevalence of psychiatric disorders equal to
0.3, type one error of 0.05 and accepted error of 0.05,
the sample size for each province was calculated equal to
825. We suggested the design effect for cluster sampling
as 1.2; so, the final sample size in each province increased
to 990 (1000). The total sample size amounted to 31 000.
The sample was selected randomly using multistage cluster
sampling method based on postal codes of houses. Our
sampling frame was all Iranian citizen aged 6 to 18 years
who lived in either urban or rural areas in each province. We
randomly selected 170 clusters of houses in each province
and each cluster included six children and adolescents
between 6 to 18 years of age. In sum, we selected about
1.000 cases from each province, except Tehran, the most
crowded province of Iran, where we selected 340 clusters
and around 2000 cases.
Survey analysis was used in the Stata software and
clustering was applied but the selection of clusters and
samples in clusters were random; we expected that the
samples’ selection probabilities were equal and our results
confirm. We were strict in interpreting the results and
have interpreted the P values above 0.01 and below 0.05
cautiously.
As mentioned, the number of people who were selected
as sample for this study was equal in all provinces. However,
the population of children and adolescence is not equal in
all provinces; hence, the data were weighted to represent
the population. We used the population weighting
adjustment based on the population distribution of
children and adolescents in each province according to the
formula below. Stata software was used for all data analysis.
1100
1000
Wij Pij
= ∗
∗
Wij: Weight of individual in each province;
Pij: Probability of individual selection in their province
More detailed information regarding the methodology
of the main study has been provided in its published
protocol.20
Instruments
Demographic data (gender, age, education, parents’
education, and economic status) was gathered using a
questionnaire designed by the investigators.
To identify the children and youth who had symptoms
of autism, the autism section of the new Kiddie Schedule
for Affective Disorders and Schizophrenia for School-Age
Present and Life time version (K-SADS-PL-2009)21 was
used. To investigate comorbid psychiatric disorders, the
K-SADS-PL was used.22 Some additional questions were
used to detect Intellectual Disability and epilepsy.
We also used the Millon Clinical Multiaxial Inventory
- Third Edition (MCMI-III) to assess parental personality
Arch Iran Med, Volume 22, Issue 10, October 2019
548
Mohammadi et al
traits and psychopathology.23
All interviews were conducted by trained clinical
psychologists.
Statistical Analysis
Descriptive statistic indices were used to obtain the
prevalence data in terms of demographic variables. All the
statistics on the prevalence of psychiatric disorders are also
based on the weighted percentages (weighting based on the
number of provincial samples) as well as crude percentages
(without weight). We used post stratification weights to
adjust the survey sample to the underlying population
demographic structure. The weighted percentages were
measured based on the population distribution of children
and adolescents across the provinces according to the
2017 national census (1 weight was assigned to every one
million people and the other weights were determined
accordingly).
Results
Table 1 presents the demographic information of the total
sample. In total, 49% of the sample were male and 51%
were female, with an age range of 6 to 18 years. Of our
participants, 83.3% lived in urban areas and 16.7% lived
in rural areas (Table 1).
The prevalence of autism in the total sample was equal to
0.1% (10/10 000), with a 2:1 male-to-female ratio (Table
1). As seen in Table 1, there are no significant differences
in the prevalence of autism based on the demographic
variables.
As Table 2 and Figure 1 demonstrate, 86% of people
with autism had at least one comorbid condition.
Intellectual Disability, epilepsy, enuresis and ADHD with
prevalence rates of 70.3%, 29.7%, 27% and 21.62%,
respectively, were the most prevalent comorbid conditions
among people with autism. There was some effect for sex
on the rate of comorbid conditions; however, it was not
statistically significant (see Table 2).
Only mothers of autistic cases filled out the Millon
inventory. The relationship between mothers’ personality
disorders and clinical scales and the prevalence of autism
is presented in Tables 3 and 4. Autism was more prevalent
among children of mothers who fell in almost all of the
diagnostic groups, but some of the differences were not
statistically significant.
Discussion
As mentioned previously, there is no clear picture regarding
Table 1. Prevalence of Autism Disorder Based on Demographic Variables in Children and Adolescents
Demographic
Variables
With Autism Disorder Binary Logistic Regression
Total, No. (%) n (Unweighted %) 95% CI %Weighted (95% CI) OR 95% CI P Value
Sex Boy 14567 (49) 22 (0.2) 0.1–0.23 0.23 (0.15–0.35) Base line
Girl 15170 (51) 15 (0.1) 0.06–0.16 0.11 (0.06–0.2) 0.65 0.34–1.26 0.21
Age group
6–9 10129 (34.1) 11 (0.1) 0.0 6–0.2 0.09 (0.04–0.2) Base line
10–14 10405 (35) 18 (0.2) 0.11– 0.27 0.29 (0.19–0.45) 1.59 0.75–3.37 0.23
15–18 9203 (30.9) 8 (0.1) 0.05–0.18 0.09 (0.04–0.21) 0.80 0.32–1.99 0.63
Place of
residence
Urban 24785 (83.3) 30 (0.1) 0.08–0.17 0.17 (0.12–0.25) Base line
Rural 4952 (16.7) 7 (0.1) 0.07–0.29 0.15 (0.05–0.43) 1.17 0.51-2.66 0.71
Father’s
education
Illiterate 1290 (4.5) 12 (0.2) 0.04–0.57 0.14 (0.02–0.79) Base line
Elementary school 4610 (16.1) 6 (0.1) 0.06–0.28 0.23 (0.10–0.50) 0.84 0.17–4.16 0.83
Middle & high school 6383 (22.3) 10 (0.2) 0.09–0.29 0.18 (0.09–0.37) 1.01 0.22–4.62 0.99
Diploma 8340 (29.1) 9 (0.1) 0.06–0.21 0.16 (0.08–0.3) 0.69 0.15–3.22 0.64
Bachelor 6053 (21.1) 7 (0.1) 0.06–0.24 0.08 (0.03–0.23) 0.75 0.15– 3.59 0.71
MSc or higher 1966 (6.9) 2 (0.1) 0.03–0.37 0.39 (0.17–0.91) 0.66 0.09–4.66 0.67
Missing 1095 1
Mother’s
education
Illiterate 1694 (5.9) 1 (0.1) 0.01–0.34 0.1 (0.02–0.58) Base line
Elementary school 5466 (18.9) 7 (0.1) 0.06–0.25 0.24 (0.12–0.50) 2.17 0.27–17.66 0.47
Middle & high school 5645 (19.5) 7 (0.1) 0.06–0.25 0.06 (0.02–0.22) 2.10 0.26–17.10 0.49
Diploma 9593 (33.1) 15 (0.2) 0.1–0.26 0.18 (0.01–0.32) 2.65 0.35-20.08 0.34
Bachelor 5555 (19.2) 7 (0.1) 0.06–0.27 .27 (0.15–0.49) 2.14 0.26-17.37 0.48
MSc or higher 986 (3.4) - - - - - -
Missing 798
Father job
Public sector 18443 (64.3) 13 (0.1) 0.08–0.24 0.17 (0.09–0.31) Base line
Private sector 9270 (32.3) 20 (0.1) 0.07–0.17 0.13 (0.08–0.21) 0.73 0.38–1.55 0.47
Unemployed 989 (3.4) 3 (0.3) 0.1–0.9 0.81 (0.35–1.88) 2.17 0.62–7.61 0.23
Missing 1035 1
Mother job
Public sector 1209 (4.2) 3 (0.1) 0.03–0.29 0.25 (0.11–0.59) Base line
Private sector 3086 (10.6) - - - - - -
Housewife 24751 (85.2) 34 (0.1) 0.1 - 0.2 0.17 (0.12–0.25) 1.41 0.43–4.6 0.57
Missing 691
Total 29737 (100) 37 (0.1) 0.09–0.17 0.18 (0.12–0.24)
Arch Iran Med, Volume 22, Issue 10, October 2019 549
Prevalence, Comorbidities and Maternal Psychopathology of ASD
Table 2. Rates of Comorbid Psychiatric Disorders in Children and Adolescents with Autism Disorder
Psychiatric Disorders Total Sex: Male (1), Female (2) Age group: 6–9 (1), 10–14 (2), 15–18 (3)
No. (%) (CI) No. (%) OR (CI) No. (%) OR (CI)
Total disorders 32 (86)
(72.03–94.9)
1 19 (86.4) 1 baseline 1 8 (80) 1 baseline
2 13 (92.9) 2.05 (.19–21.97) 2 16 (88.9) 2.00 (.24–16.93)
3 7 (86.5) 1.75 (.13–23.70)
Depressive 1 (2.7)
(0.5–1.38)
1 1 (4.5) 1 baseline 1 0 1 baseline
2 0 0 2 0 —
3 1 (12.5) —
Anxiety
disorders
Separation anxiety disorder 5 (13.5) (5.91–27.97)
1 2 (9.1) 1 baseline 1 0 1 baseline
2 3 (20) 2.5 (0.36–17.2) 2 4 (22.2) —
3 1 (12.5) —
Social phobia 7 (19) (9.5–34.21)
1 5 (23.8) 1 baseline 1 1 (9.1) 1 baseline
2 2 (13.3) 0.49 (0.08–2.97) 2 5 (29.4) 4.17 (0.42–41.78)
3 1 (12.5) 1.43 (0.08–26.89)
Specific phobia 1 (2.7) (0.5–1.38)
1 0 1 baseline 1 0 1 baseline
2 1 (6.7) 0 2 0 —
3 1 (12.5) —
Agoraphobia 1 (2.7) (0.5–1.38)
1 0 1 baseline 1 0 1 baseline
2 1 (6.7) 0 2 0 —
3 1 (12.5) —
Generalized anxiety disorder 5 (13.5) (5.91–27.97)
1 4 (18.2) 1 baseline 1 0 1 baseline
2 1 (7.1) 0.35 (0.03–3.5) 2 3 (16.7) —
3 2 (28.6) —
Obsessive compulsive
disorder 5 (13.5) (5.91–27.97)
1 3 (13.6) 1 baseline 1 0 1 baseline
2 2 (13.3) 0.97 (14–6.67) 2 2 (11.1) —
3 3 (37.5) —
Total anxiety disorders 10 (27) (15.4–42.98)
1 6 (27.3) 1 baseline 1 1 (9.1) 1 baseline
2 4 (50) 1.39 (0.32–5.89) 2 6 (33.3) 4.91 (0.50–48.62)
3 4 (50) 9 (0.75–108.3)
Behavioral
Disorders
Attention deficit
hyperactivity disorder 8 (21.6) (11.39–37.19)
1 7 (33.3) 1 baseline 1 3 (27.3) 1 baseline
2 1 (6.7) 0.14 (0.01–1.32) 2 4 (23.5) 0.82 (0.14–4.66)
3 1 (12.5) 0.38 (0.03–4.55)
Conduct disorder 1 (2.7) (0.5–1.38)
1 1 (4.5) 1 baseline 1 0 1 baseline
2 0 0 2 1 (5.6) —
3 0 —
Oppositional defiant
disorder 6 (16.2) (7.65–31.14)
1 4 (18.2) 1 baseline 1 1 (9.1) 1 baseline
2 2 (13.3) 0.69 (0.11-4.36) 2 4 (22.2) 2.85 (0.28–29.56)
3 1 (12.5) 1.43 (0.08–26.89)
Tic disorder 3 (8.1) (2.8–21.3)
1 3 (13.6) 1 baseline 1 0 1 baseline
2 0 0 2 3 (16.7) —
3 0 —
Total behavioral disorders 11 (29.7) (17.49–45.78)
1 9 (40.9) 1 baseline 1 3 (27.3) 1 baseline
2 2 (13.3) 0.21 (0.4–1.1) 2 7 (38.9) 1.87 (0.36–9.63)
3 1 (12.5) 0.38 (0.03–4.55)
Intellectual disability 26 (70.3) (54.22–82.51)
1 15 (68.2) 1 baseline 1 6 (54.5) 1 baseline
2 11 (73.3) 1.28 (0.3–5.5) 2 13 (72.2) 2.17 (0.45–10.43)
3 7 (87.5) 5.83 (0.52–64.82)
Epilepsy 11 (29.7) (17.49–45.78)
1 8 (36.4) 1 baseline 1 2 (18.2) 1 baseline
2 3 (20) 0.44 (0.09–2) 2 7 (38.9) 2.86 (0.47–17.35)
3 2 (25) 1.50 (0.16–13.75)
Total neurodevelopmental
disorders
28 (75.7) (59.9–86.6) 1 17 (77.3) 1 baseline 1 7 (63.6) 1 baseline
2 11 (73.3) 0.8 (0.18–3.6) 2 14 (77.8) 2 (0.38–10.48)
3 7 (87.5) 4 (0.35–45.38)
Elimination
Disorders
Enuresis 10 (27) (15.4–42.98)
1 7 (31.8) 1 baseline 1 3 (27.3) 1 baseline
2 3 (20) 0.54 (0.11–2.5) 2 5 (27.8) 1.03 (0.19–5.50)
3 2 (25) 0.89 (0.11–7.11)
Encopresis 4 (10.8) (4.28–24.71)
1 2 (9.1) 1 baseline 1 1 (9.1) 1 baseline
2 2 (13.3) 1.53 (0.2–12.3) 2 2 (11.1) 1.25 (0.1–15.65)
3 1 (12.5) 1.43 (0.08–26.9)
Total Elimination Disorders 10 (27) (15.4–42.98)
1 7 (31.8) 1 baseline 1 3 (27.3) 1 baseline
2 3 (20) 0.54 (0.11–2.5) 2 5 (27.8) 1.03 (0.19–5.51)
3 2 (25) 0.89 (0.11–7.11)
Arch Iran Med, Volume 22, Issue 10, October 2019
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Mohammadi et al
the prevalence of autism and its comorbidities among
Iranian children and adolescents and the present study is
the first national population-based study to address these
issues.
Previous studies have shown heterogeneity in estimated
prevalence of autism around the world; in a systematic
review, its median was reported at 62 per 10 000.24 The
current study has estimated the prevalence of autism
at 0.1% (or 10 per 10 000) in a large sample of Iranian
children and adolescents. This rate is close to and in fact
higher than the previously reported prevalence of typical
autism in Iran (i.e. 6.26 per 10 000). Like previous studies,
in this study, the prevalence rate is higher in male subjects
compared to females (0.1% in females vs. 0.2% in males),
although the difference is not statistically significant (OR:
0.65, CI: 0.34–1.26). However, the male-to-female ratio
reported in this study (2:1) is lower than the results of
previous studies (i.e. 3:1to 4:1).
Comorbid conditions were common in our sample; 86%
(CI:72.03–94.9) of participants had at least one comorbid
condition. Intellectual disability (MR) with 70.3% (CI:
54.22–82.51) was the most prevalent comorbidity. This
high rate of MR among our ASD positive cases can explain
the low prevalence rate of autism in the total sample; it
seems that we only detected the severe cases of autism.
Some researchers argue that the prevalence of MR is higher
in female subjects with autism compared to male subjects;
we found a similar pattern in our study (OR: 1.28, CI:
0.3–5.5).
A national survey on 85 248 children and adolescents
aged between 2-17 years has shown that 8.6% of ASD
cases had comorbid epilepsy,25 while in our study, this rate
was found to be 29.7% (CI: 17.49–45.78) of the ASD
cases. In addition to the high prevalence of MR, this high
rate of epilepsy compared with other similar studies reveals
that our detected ASD cases fall in the range of severe
symptoms.
Previous studies have shown that rates of enuresis in
ASD cases are 2–16%.26 We found this rate to be 27%
1
2.7
2.7
2.7
2.7
8.1
10.8
13.5
13.5
13.5
16.2
19
21.62
27
29.7
70.3
86
010 20 30 40 50 60 70 80 90 100
Depressive
Specific Phobias
Agoraphobia
Conduct disorder
Tic Disorder
Encopresis
Separate anxiety disorder
Generalized Anxiety
Obsessive Compulsive Disorder
Oppositional Defiant Disorder
Social Phobia
Attention Deficit Hyperactivity Disorder
Enuresis
Epilepsy
Mental retardation
total comorbid disorders
Figure 1. Rate of Comorbid Disorders in Autism Spectrum
Disorder in Percent.
(CI: 15.4–42.98) in our study. One important factor that
increases enuresis in people with ASD is the adverse effect
of medication.26 Given the high prevalence of comorbid
conditions in our sample, especially MR and epilepsy,
these people were subject to taking more medications27
and thus, some proportion of this co-occurring enuresis
may be due to using medications.
Attention deficit and hyperactivity disorder (ADHD),
with a prevalence of 21.62%, was the next common
comorbid psychiatric disorder in our sample of ASD cases.
This observation is in the range of the findings of previous
similar studies.27
In our sample of children and adolescents with
ASD, there were other comorbid conditions, including
social phobia, oppositional defiant disorder, obsessive
compulsive disorder, generalized anxiety, separation
anxiety, encopresis, tic, conduct, agoraphobia, specific
phobia and depression with prevalence rates of 19%,
16.2%, 13.5%, 13.5%, 13.5%, 10.8%, 8.1%, 2.7%,
2.7%, 2.7% and 2.7%, respectively. This large number
and variety of comorbid conditions should be considered
in planning therapeutic programs for children with autism.
These can adversely affect the outcomes of interventions
and can also complicate the management of the child’s
behaviors.
Some studies have revealed sex differences in comorbid
conditions among children with autism. For example, it
has been shown that ADHD is more common in males
compared to females.11 Our study also showed these sex
differences; however, they were not statistically significant.
For example, ADHD was more prevalent in male
participants (odds ratio [OR]: 0.14, CI: 0.01–1.32) while
separation anxiety was more prevalent in females (OR: 2.5,
CI: 0.36–17.2). We also found some differences between
age groups (i.e. 6–9, 10–14 and 15–18 years) regarding
comorbidities. Anxiety disorders (OR: 4.91, CI: 0.50–
48.62, OR: 9, CI: 0.75–108.3) and neurodevelopmental
disorders (OR: 2, CI: 0.38–10.48, OR: 4, CI: 0.35–45.38)
were more prevalent in older age groups. This pattern can
be explained by the fact that people with autism are going
to be more deprived with increasing age and will feel more
anxious facing the pressure of increasing social demands.
Behavioral disorders increased in middle childhood (OR:
1.87, CI: 0.36–9.63) and then decreased (OR: 0.38, CI:
0.03–4.55). Importantly, it should be noted that due to the
small number of ASD cases and wide range of confidence
intervals, this finding should be considered with caution.
As seen in Tables 3 and 4, maternal personality disorders
were associated with increasing risk of autism. This
association was statistically significant among mothers
who were at risk of schizoid (OR: 5.25, CI:1.25–22.03),
melancholic (OR: 3.33, CI: 1.28–8.66) and persistent
depression (OR: 5.12, CI: 1.55–16.85) and also those who
were diagnosed with schizoid (OR: 21.86, CI: 2.91-164.04)
and posttraumatic stress disorder (OR: 10.14, CI:1.37–
Arch Iran Med, Volume 22, Issue 10, October 2019 551
Prevalence, Comorbidities and Maternal Psychopathology of ASD
75.03). This finding is in line with the results of previous
studies conducted in other countries. A population-based
study in Sweden28 reported that schizophrenia was more
common among both parents of children with autism, in
comparison to non-autistic children. However, depression
and personality disorders were more prevalent only among
mothers of children with autism. Another population-
based study in Finland investigated the relationship
between parental psychiatric disorders and the risk of ASD
in children based on its subgroups (i.e. childhood autism,
Asperger syndrome and PDD-NOS).18 This study showed
that there was a relationship between increased risk of ASD
and the presence of maternal and paternal schizophrenia,
affective disorders, neurotic and personality disorders and
other nonpsychotic disorders. However, there are some
differences between maternal and paternal effects among
ASD subgroups. Paternal schizophrenia, affective disorders,
and neurotic and personality disorders were associated with
risk of childhood autism, whereas only maternal affective
disorders were associated with that risk. Also, Asperger
syndrome was associated with schizophrenia, affective
disorders, neurotic and personality disorders and other
nonpsychotic disorders in mothers and affective disorders,
neurotic and personality disorders and other nonpsychotic
disorders in fathers. PDD-NOS was also associated with all
parental psychiatric disorders. In summary, this observed
Table 3. Odds Ratios (95% CI) for Children and Adolescents with Autism Disorders Based on Maternal Personality Disorders
Maternal Personality
Disorders
Diagnostic
Labels
Children with
Autism disorders, No. (%)
Univariate Multivariate
OR (CI 95%) P Value OR (95% CI) P Value
Clinical pattern
of personality
disorders
Schizoid
No 31 (0.1) Baseline
At risk 2 (0.6) 5.25 (1.25–22.03) 0.023 4.56 (0.92–22.62) 0.063
Yes 1 (2.4) 21.86 (2.91–164.04) 0.003 18.58 (1.73–20.05) 0.016
Avoidant
No 33 (0.1) Baseline
At risk 1 (0.4) 3.38 (0.46–24.79) 0.24 1.23 (0.13–11.88) 0.861
Yes 0 — — — —
Melancholic
No 27 (0.1) Baseline
At risk 5 (0.4) 3.33 (1.28–8.66) 0.014 2.66 (0.94–7.58) 0.067
Yes 2 (0.2) 1.54 (0.37–6.49) 0.56 0.69 (1.08–4.469) 0.701
Dependent
No 34 (0.1) Baseline
At risk 0 — — — —
Yes 0 — — — —
Histrionic
No 26 (0.1) Baseline
At risk 5 (0.1) 0.95 (0.36–2.48) 0.92 1.11 (0.42–2.93) 0.842
Yes 3 (0.1) 0.80 (0.24–2.63) 0.71 0.94 (0.28–3.19) 0.926
Narcissistic
No 33 (0.1) Baseline
At risk 1 (0.1) 0.71 (0.1–5.18) 0.73 0.62 (0.08–4.62) 0.640
Yes 0 — — — —
Anti-social No 34 (0.1) Baseline
At risk 0 — — — —
Yes — — — — —
Sadistic
No 34 (0.1) Baseline
At risk 0 — — — —
Yes 0 — — — —
Obsessive
compulsive
No 24 (0.1) Baseline
At risk 3 (0.1) 1.20 (0.36–3.99) 0.76 1.16 (0.35–3.87) 0.809
Yes 7 (0.1) 1.26 (0.54–2.94) 0.58 1.26 (0.54–2.95) 0.592
Negativistic
No 31 (0.1) Baseline
At risk 3 (0.3) 2.34 (0.71–7.68) 0.16 1.24 (0.29–5.25) 0.775
Yes 0 — — — —
Masochistic No 34 (0.1) Baseline
At risk 0 — — — —
Yes 0 — — — —
Severe
Personality
Pathology
scales
Schizotypal
No 33 (0.1) Baseline
At risk 1 (0.6) 5.01 (0.68–36.85) 0.12 2.27 (0.21–24.73) 0.501
Yes 0 — — — —
Borderline
No 34 (0.1) Baseline
At risk 0 — — — —
Yes 0 — — — —
Paranoid
No 34 (0.1) Baseline
At risk 0 — — — —
Yes 0 — — — —
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552
Mohammadi et al
relationship between parental psychiatric disorders and
risk of autism is twofold. First, like in previous studies,
this supports the idea that autism can have a genetic basis
which is common with other psychiatric disorders to some
extent; second, it indicates that we should consider the
presence of psychiatric disorders among autistic families in
interventional programs.
In summary, based on the results of the present study,
it may be stated that the estimated prevalence of autism
among Iranian children and adolescents is 0.1% (10 per
10 000); however, it seems that this prevalence represents
cases who have more severe symptoms of autism.
Comorbid psychiatric disorders are common among
autistic cases. Intellectual Disability, epilepsy, enuresis
and ADHD are the most prevalent comorbid conditions
in people with autism. These high rates of comorbid
conditions should be considered in interventional
programs.
Our findings also show that there is a relationship
between some maternal psychiatric disorders and risk of
autism, which is assumed to reveal a shared genetic basis
between autism and other psychiatric disorders.
Limitations
The most notable limitation of the present study is that
based on the data gathering procedure and diagnostic tool,
the estimated prevalence could not reflect the number
of all suspected ASD cases among Iranian children and
adolescents; rather, it only reveals the prevalence of severe
cases of autism.
As seen in Table 2, the presence of huge confidence limits
and wide confidence intervals suggests sparse-data bias
and imprecision.29 This should be noted as an important
limitation of this study that can influence our findings.
Regarding parental psychiatric disorders, we only had the
mothers’ data and thus, we could not depict a full picture
of psychiatric disorders among parents of Iranian children
with autism.
Authors’ Contribution
MRM, NA, AKh, HZ, SAM, KK and MR prepared study proposal. All
authors are involved in the data gathering process. HZ generated
study hypotheses and drafted the manuscript. ZH analyzed data. All
authors read and approved the final manuscript.
Conflict of Interest Disclosures
None declared.
Table 4. Odds Ratios (%95 CI) for Children and Adolescents with Autism Disorders Based on Maternal Clinical Scale
Mother Personality
Disorders
Diagnostic
Labels
Children with Autism
Disorders, No. (%)
Univariate Multivariate
OR (95% CI) P Value OR (95% CI) P Value
Clinical
Syndrome
Scales
Anxiety
No 33 (0.1) Baseline
At risk 0 — — — —
Yes 1 (0.4) 3.13 (0.43–22.96) 0.26 1.13 (.07–18.59) .932
Somatoform
No 32 (0.1) Baseline
At risk 2 (0.5) 3.89 (0.93–16.29) 0.063 1.62 (.27–9.68) .597
Yes 0 — — — —
Bipolar spectrum
No 34 (0.1) Baseline
At risk 0 — — — —
Yes 0 — — — —
Persistent Depression
No 29 (0.1) Baseline
At risk 3 (0.6) 5.12 (1.55–16.85) 0.007 5.65 (1.61–19.85) .007
Yes 2 (0.4) 3.35 (0.80–14.09) 0.098 3.58 (.55–23.36) .182
Alcohol dependence
No 34 (0.1) Baseline
At risk 0 — — — —
Yes — — — — —
Drug dependence
No 34 (0.1) Baseline
At risk 0 — — — —
Yes 0 — — — —
Posttraumatic stress
disorder
No 33 (0.1) Baseline
At risk 0 — —
Yes 1 (1.2) 10.14 (1.37–75.03) 0.023 4.27 (.24–75.29) .321
Severe
Clinical
Syndrome
scales
Schizophrenic
Spectrum
No 33 (0.1) Baseline
At risk 1 (0.5) 3.88 (0.53–28.46) 0.18 1.47 (.13–16.60) .756
Yes 0 — — — —
Major Depression
No 34 (0.1) Baseline
At risk 0 — — — —
Yes 0 — — — —
Delusional Disorder
No 34 (0.1) Baseline
At risk 0 — — — —
Yes 0 — — — —
Arch Iran Med, Volume 22, Issue 10, October 2019 553
Prevalence, Comorbidities and Maternal Psychopathology of ASD
Ethical Statement
The Ethics Committee Board of the National Institute for Medical
Research Development (NIMAD) has approved this study (the ethics
code: IR.NIMAD.REC.1395.001).
Funding
The study was supported by grant 940906 from the National Institute
for Medical Research Development (NIMAD).
Role of the Funder/Sponsor
The sponsors had no additional role in the design and conduct of the
study; collection, management, analysis, and interpretation of the data;
and preparation, review, or approval of the manuscript; and decision to
submit the manuscript for publication.
Acknowledgments
First of all, thanks to the participants and their families. Then, thanks
to the head, staff and the Neuroscience committee of the National
Institute for Medical Research Development (NIMAD) that financially
supported this study with grant number 940906. Especially, many
thanks to Dr. Bita Mesgarpour and Dr. Sofia Esalatmanesh.
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