Epidemiology Autism

reports of autism cases per 1,000 children grew dramatically in 1996 2007. unknown how much, if any, growth came changes in rates of autism.

most recent reviews tend estimate prevalence of 1–2 per 1,000 autism , close 6 per 1,000 asd, , 11 per 1,000 children in united states asd of 2008; because of inadequate data, these numbers may underestimate asd s true rate. globally, autism affects estimated 24.8 million people of 2015, while asperger syndrome affects further 37.2 million. in 2012, nhs estimated overall prevalence of autism among adults aged 18 years , on in uk 1.1%. rates of pdd-nos s has been estimated @ 3.7 per 1,000, asperger syndrome @ 0.6 per 1,000, , childhood disintegrative disorder @ 0.02 per 1,000. cdc s recent estimate 1 out of every 68 children, or 14.7 per 1,000, has asd of 2010.

the number of reported cases of autism increased dramatically in 1990s , 2000s. increase largely attributable changes in diagnostic practices, referral patterns, availability of services, age @ diagnosis, , public awareness, though unidentified environmental risk factors cannot ruled out. available evidence not rule out possibility autism s true prevalence has increased; real increase suggest directing more attention , funding toward changing environmental factors instead of continuing focus on genetics.

boys @ higher risk asd girls. sex ratio averages 4.3:1 , modified cognitive impairment: may close 2:1 intellectual disability , more 5.5:1 without. several theories higher prevalence in males have been investigated, cause of difference unconfirmed; 1 theory females underdiagnosed.

although evidence not implicate single pregnancy-related risk factor cause of autism, risk of autism associated advanced age in either parent, , diabetes, bleeding, , use of psychiatric drugs in mother during pregnancy. risk greater older fathers older mothers; 2 potential explanations known increase in mutation burden in older sperm, , hypothesis men marry later if carry genetic liability , show signs of autism. professionals believe race, ethnicity, , socioeconomic background not affect occurrence of autism.

several other conditions common in children autism. include:

genetic disorders. 10–15% of autism cases have identifiable mendelian (single-gene) condition, chromosome abnormality, or other genetic syndrome, , asd associated several genetic disorders.
intellectual disability. percentage of autistic individuals meet criteria intellectual disability has been reported anywhere 25% 70%, wide variation illustrating difficulty of assessing intelligence of individuals on autism spectrum. in comparison, pdd-nos association intellectual disability weaker, , definition, diagnosis of asperger s excludes intellectual disability.
anxiety disorders common among children asd; there no firm data, studies have reported prevalences ranging 11% 84%. many anxiety disorders have symptoms better explained asd itself, or hard distinguish asd s symptoms.
epilepsy, variations in risk of epilepsy due age, cognitive level, , type of language disorder.
several metabolic defects, such phenylketonuria, associated autistic symptoms.
minor physical anomalies increased in autistic population.
preempted diagnoses. although dsm-iv rules out concurrent diagnosis of many other conditions along autism, full criteria attention deficit hyperactivity disorder (adhd), tourette syndrome, , other of these conditions present , these comorbid diagnoses increasingly accepted.
sleep problems affect two-thirds of individuals asd @ point in childhood. these commonly include symptoms of insomnia such difficulty in falling asleep, frequent nocturnal awakenings, , morning awakenings. sleep problems associated difficult behaviors , family stress, , focus of clinical attention on , above primary asd diagnosis.




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