Prevalence of autism
in children born to
Somali parents living
in Sweden: a brief
Martina Barnevik–Olsson MD, Department of Child and
Adolescent Psychiatry, Järva BUP, Stockholm;
Christopher Gillberg MD PhD, Department of Child and
Adolescent Psychiatry, University of Gothenburg;
Elisabeth Fernell* MD PhD, Habilitation Centre for
Pre-School Children with Autism, Stockholm, Sweden.
In a geographical area of Stockholm, with a relatively large
Somali immigrant population, parents as well as teachers in
special schools and staff at habilitation centres have raised
concerns over whether children with a Somali background are
over-represented in the total group of children with autism.
The aim of the study was, therefore, to investigate the
prevalence of autism in children with parents from Somalia,
living in Stockholm county, and to compare the prevalence in
children of Somali background with that in the non-Somali
group. We reviewed the records of 17 children (13 males,
four females), born between 1988 and 1998 (age range
7–17y) and with a Somali background, who had a diagnosis
of autistic disorder or pervasive developmental disorder not
otherwise specified (PDDNOS) and were registered at either
of the two autism habilitation centres for school-aged
children. The prevalence of autistic disorder or PDDNOS was
found to be three to four times higher than in the non-Somali
group (0.7% vs 0.19%). All children also had learning
disability.* Our findings warrant further investigations of
possible aetiological factors behind the increased prevalence
of autistic disorders in children of Somali origin found in this
area in Sweden.
ger syndrome, and pervasive developmental disorder not
otherwise specified (PDDNOS).Manyindividuals,particularly
those with themost severeand ‘classic’ variants of autistic dis-
In some children the underlying aetiology can be demon-
strated, such as when a specific syndrome or a neurological
condition is diagnosed, including tuberous sclerosis, fragile
X syndrome, or Moebius syndrome. However, at present,
despite a thorough medical investigation, a definite medical
condition can be identified only in a minority of children
Genetic factors are very important,3,4
although the exact genetic mechanisms are currently not
known. Several susceptibility genes have been discussed, and
some cases are clearly due to (or are partly caused by) spe-
cific mutant genes.5The rate of autism is much higher in
monozygotic twins than in dizygotic twins, and the condition
is more prevalent in males.1
Idiopathic autism is a very challenging condition for par-
ents. Along with genetic aspects, several other explanations
have been discussed, including the influence of diet, intesti-
nal inflammation, and vaccination. In a geographical area of
Stockholm, with a relatively large Somali immigrant popula-
tion, many parents of Somali children have refrained from
letting their child be given the measles, mumps, and rubella
(MMR) vaccine because of the controversial (and now
refuted) link between MMR vaccination and autism.6In that
specific area of Stockholm, vaccination frequency was 69.5%
in 2005, and 71% in 2006, in comparison to about 95% in
most other areas in Stockholm.7In this area in the northwest-
ern part of Stockholm, parental concern about the risk of
vaccination coincides with concerns from teachers and
autism assessment teams about a seemingly higher than
expected proportion of Somali children having autism.
people and about 20 000 births per year during the studied
birth-year period), and to compare the prevalence in children
of Somali background with that in the non-Somali group of
children in the same area. Our hypothesis was that the preva-
lence of autism in the group of children with Somali back-
In the county of Stockholm, school-age children (age range
PDDNOS according to DSM-IV,8in conjunction with learning
disabilityare referred for intervention and follow-up to oneof
The target population consisted of all children aged 7 to 17
years (birth years 1988–1998) and living in the county of
Stockholm in November 2005 (n=253 002).
CHILDREN OF SOMALI BACKGROUND
Children of Somali background were those who were either
born in Somalia or born in Sweden, with both parents born
abroad and at least one parent coming from Somalia, as
defined by the Swedish Central Bureau of Statistics.9In
Developmental Medicine & Child Neurology 2008, 50: 598–601
November 2005, this group consisted of 2437 7- to 17-year-
olds. Children with a Somali background constituted 0.96%
(2437⁄253 002) of the total child population born during
1988 to 1998 in the county.
Parents with a Somali origin were asked by a letter, with
information written in Swedish and Somali, to let one of
the authors (MBO) have access to their child’s records
from the habilitation centre. All records of children in the
age group with a Somali background, who were registered
at either one of the two habilitation centres and who had
a diagnosis of autistic disorder or PDDNOS, were reviewed,
and their status as regards Somali background was deter-
mined. All records were scrutinized regarding antenatal,
perinatal, and postnatal data, medical information, and
data from the assessment supporting the diagnosis of
autism. Two of the authors (MBO and EF) made certain
that DSM-IV criteria for autistic disorder or PDDNOS were
met in all individuals registered as having autistic disorder
The study was approved by the regional ethics committee
A total of 501 children (0.2% of the total child population,
with a male:female ratio of 3:1) had a diagnosis of autistic dis-
order or PDDNOS and were registered at either of the two
habilitation centres for children with autistic disorder or
PDDNOS in Stockholm in 2005. Seventeen (13 males, four
females, population-adjusted male:female ratio 3.3:1) of the
501 children with autistic disorder (n=14) or PDDNOS
(n=3; 3.4% of all with autistic disorder or PDDNOS) had a
Somali background. Fifteen of these were registered at the
north centre and two at the south centre.
The minimum prevalence of autistic disorder or PDDNOS
was 0.7% (17 of 2437; 95% confidence interval [CI] 0.37–
1.03) among children with a Somali background. Among the
children with a non-Somali background the corresponding
prevalence was 0.19% (484 of 250 565; 95% CI 0.18–0.21;
Data from records revealed that most of the children (13 of
17) had three or more siblings. One female had a brother
(not in the study group) with autism and learning disability.
One male with autism and learning disability had two non-
study-group siblings with learning disability (but no autism)
and yet another male with autism and learning disability had
a non-study-group sibling with autism. Six of the 17 children
with autistic disorder or PDDNOS were the parents’ first-
born child. In all children, except one, both parents had a
Somali origin. One child had a father from another country
on the Horn of Africa.
Information on the time of arrival in Sweden was mostly
not given in the records. In one case it was mentioned that
the mother moved to Sweden during pregnancy.
Consanguinity was reported in the records for three indi-
viduals, parents being first cousins for one child and second
cousins for another; a more remote relationship was
declared for the third. This information had not regularly
been requested during assessments. All 17 children had been
born in Sweden. Gestational ages could be identified in the
available records for 15 of the 17 children; all these were
born at term. Available data demonstrated that one child had
been born small for gestational age and had had mild hypo-
glycaemia, one had had mild asphyxia, and one had suffered
from mild respiratory distress.
Most (14 of 17) of the children had presented signs of
arrested development, mainly in the progression of speech
and language, at an age of about 12 to 24 months. For one
child developmental deviation was reported at an age of
about 6 months, and for two children information was lack-
ing. Learning disability, assessed with the Griffiths scales in
most of the children, or strongly clinically suspected, were
reported for 16 of the 17 children. One child was reported to
have a borderline intellectual functioning but attended a spe-
cial school for children with learning disability. Profound
hyperactivity was reported in at least 13 of the 17 children.
This hyperactivity was described as ‘tears down the visiting
room’ or ‘constantly touching everything’. One child had a
congenital bilateral deafness but no other symptoms or signs
pertaining to a specific syndrome. One child had epilepsy,
but it was not possible from available records to identify the
type. General motor function was not a problem in most of
the children; only one child who also had bilateral deafness
had delayed motor development.
Our hypothesis that the prevalence of autistic disorder or
PDDNOS was increased in children with a Somali back-
ground living in Sweden was confirmed. The prevalence was
threefold to fourfold that in children of non-Somali origin liv-
ing in the county (0.7% vs 0.19%). At the habilitation centres,
children from Somalia constituted 3.4% (17 of 501) and the
rate of Somali children in the county was 0.96% (2437 of
One limitation of this study is the retrospective collection
of data, relying on clinical notes that had not been intended
for research. Only the autistic disorder or PDDNOS diagno-
ses for the Somali children were checked and reconfirmed.
The data are therefore not complete and must be seen as
preliminary. In addition, the study group was small, consist-
ing of 17 children, assessed by different teams. However, 10
of them had been assessed at the same child neuropsychi-
atric unit in the county or this team had been consulted
during the assessment, three of the children were assessed
at other habilitation units in Sweden and the remainder
were assessed by different neuropsychiatric⁄neuropaediatric
teams in Stockholm. Assessments were performed similarly
and all met criteria for autistic disorder or PDDNOS accord-
ing to DSM-IV criteria. All 17 children and their parents had
continued their contact for several years with the two habili-
tation centres that were exclusively aimed at children with
autism-spectrum disorders in conjunction with learning
Our clinical impression is that this group of Somali chil-
dren constitutes a rather homogeneous group in the autism
spectrum with regard to four characteristics: (1) the age at
which the developmental deviation was noted (12–24mo);
(2) the presence of a definite intellectual impairment in all
17 individuals, mostly of a moderate to severe degree; (3) the
fact that motor function was not impaired, except in one
Autism in Children Born to Somali Parents in Sweden Martina Barnevik–Olsson et al.
child; and (4) the fact that the activity level was exceptionally
raised in the vast majority of the children.
The origins of the autistic disorder or PDDNOS in these
children is not apparent. No definite perinatal or postnatal
causes were revealed. Males dominated in the Somali popula-
In our study group the children had both parents coming
from Somalia, except for one child who had a father from a
country near Somalia. The vast majority of the mothers
had been settled in Sweden during the entire pregnancy. We
had insufficient data about the number of mothers who had
arrived in Sweden during pregnancy: only for one mother
was this reported in the child’s medical record.
All individuals had learning disability. This is a develop-
mental disorder in which genetic background factors have a
prominent role. Recessive inheritance has been especially
demonstrated in severe learning disability.10In many parts of
the world, especially the Islamic countries, marriages
between close relatives are common.11,12In a previous study
from Stockholm county,13covering a population with a high
rate of non-European⁄non-North American immigrants, the
prevalence of severe learning disability was found to be 3.7
and 5.9 per 1000 respectively, in the European and in the
Consanguineous marriages were assumed to be a factor of
importance in the distribution of aetiologies of severe learn-
ing disability in that study. In the present study it was not
possible to obtain information about consanguinity in most
of the families, but this factor cannot be excluded as being of
crucial importance. Differences between European and non-
European groups of children with mental disabilities in the
UK were studied by Akinsola and Fryers,14also reporting
more severe disabilities in the non-European group.
Increased prevalence rates of autism in children of immi-
grants of African origin have been previously reported in
Sweden.15,16Gillberg found a remarkably high prevalence in
males from Uganda. In another study he discussed the possi-
bility that some of the increased rate of autism in this sub-
population of migrants to Sweden from Africa and other
remote regions might be attributable to autism-spectrum
conditions in the father rather than to the immigrant status
of the mother. Several fathers of children in one of the stud-
ies were of Swedish descent. However, in the Somali sample
reported in the present context there was no indication of
Knowledge about genes linked to susceptibility for the
development of autism and autism-spectrum disorders is
increasing.17McMahon et al. discuss the fact that there is cur-
rently no genetic test to determine the risk of autism, but it is
possible that such tests may emerge in the near future. They
also emphasize, like Gillberg and Coleman,1that autism
represents complex, multifactorial conditions.
Recently, in a Norwegian study, Kanavin and collabora-
tors18reported that a 4-year-old male with autism, learning
disability, and epilepsy, and with a Somali background, was
found to have a metabolic disturbance, a defect in the degra-
dation pathway of the amino acid L-isoleucine. The under-
lying gene defect could be detected. The authors were also
able to identify this mutation in another two children from
Somalia and Eritrea respectively.
The possibility of epigenetic factors operating in autism
has been discussed by Zhao and colleagues,19for example,
they concluded that disturbances in epigenetic modulations
and regulations can lead to inappropriate expression or
silencing of genes. It is hoped that our understanding of such
mechanisms will increase in the future.
From a neuropaediatric⁄neuropsychiatric point of view, our
findings warrant further investigations of possible aetiologi-
cal factors behind the increased prevalence of autistic dis-
orders in children with Somali origin. Yet, irrespective of
aetiology, this group of children and their families need com-
prehensive habilitation measures and long-term support and
Accepted for publication 19th March 2008.
We are grateful to valuable collaboration with Eva Klintemar,
Claudia Chavez Martinez, Ann-Louise Östling Lind, and Methe
Axén, representing the habilitation centres for children with
autism in Stockholm, and to Gunnel Bågenholm at the Depart-
ment of Preventive Child Health, Karolinska University Hospital,
1. Gillberg C, Coleman M. The biology of the autistic syndromes.
3rd edn. Clinics in Developmental Medicine No. 153⁄4.
London: MacKeith Press, 2000.
2. Medical Research Council. MRC Review of autism research.
Epidemiology and causes. London: MRC, 2001.
3. Wassink TH, Brzustowicz LM, Bartlett CW, Szatmari P. The
search for autism disease genes. Ment Retard Dev Disabil Res
Rev 2004; 10: 272–83.
4. Szatmari P, Paterson AD, Zwaigenbaum L, Roberts W, Brian J,
Liu XQ, et al. Mapping autism risk loci using genetic linkage
and chromosomal rearrangements. Nat Genet 2007;
5. Jamain S, Quach H, Betancur C, Råstam M, Colineaux C,
Gillberg IC, et al. Mutations of the X-linked genes encoding
neuroligins NLGN3 and NLGN4 are associated with autism.
Nat Genet 2003; 34: 27–29.
6. Taylor B. Vaccines and the changing epidemiology of autism.
Child Care Health Dev 2006; 32: 511–19.
7. Blennow M. Child health report. Stockholm: Stockholm
8. American Psychiatric Association. Diagnostic and Statistical
Manual of Mental Disorders. 4th edn. Arlington, VA: American
Psychiatric Association, 1994.
9. Statistiska Centralbyrån, SCB. Statistics Sweden. Population
statistics, demographics of Sweden. 2005.
10. Beke A, Papp Z. Genetic components of perinatal morbidity
and mortality. J Perinat Med 2001; 29: 230–34.
11. Editorials. Consanguinity and health. Lancet 1991;
12. Freire-Maia N. Inbreeding levels in different countries.
Soc Biol 1982; 29: 69–81.
13. Fernell E. Aetiological factors and prevalence of severe mental
retardation in children in a Swedish municipality: the possible
role of consanguinity. Dev Med Child Neurol 1998;
14. Akinsola HA, Fryers T. A comparison of patterns of disability
in severely mentally handicapped children of different ethnic
origins. Psychol Med 1986; 16: 127–33.
15. Gillberg C, Schaumann H, Gillberg IC. Autism in immigrants:
children born in Sweden to mothers born in Uganda.
J Intellect Disabil Res 1995; 39: 141–44.
16. Gillberg IC, Gillberg C. Autism in immigrants: a population-
based study from Swedish rural and urban areas. J Intellect
Disabil Res 1996; 40: 24–31.
17. McMahon WM, Baty BJ, Botkin J. Genetic counseling and
ethical issues for autism. Am J Med Genet 2006; 142: 52–57.
Developmental Medicine & Child Neurology 2008, 50: 598–601
18. Kanavin OJ, Woldseth B, Jellum E, Tvedt B, Andresen BS,
Stromme P. 2-methylbutyryl-CoA dehydrogenase deficiency
associated with autism and mental retardation: a case report.
J Med Case Rep 2007; 1: 98.
19. Zhao X, Pak C, Smrt RD, Jin P. Epigenetics and neural
developmental disorders. Epigenetics 2006; 2: 126–34.
List of abbreviations
Measles, mumps, and rubella
Pervasive developmental disorder not otherwise speci-
Autism in Children Born to Somali Parents in Sweden Martina Barnevik–Olsson et al.