Featured Research

from universities, journals, and other organizations

Rise In Autism Is Related To Changes In Diagnosis, New Study Suggests

Date:
April 9, 2008
Source:
Wellcome Trust
Summary:
New research suggests that many children diagnosed with severe language disorders in the 1980s and 1990s would today be diagnosed as having autism. The research supports the theory that the rise in the number of cases of autism may be related to changes in how it is diagnosed.

New research suggests that many children diagnosed with severe language disorders in the 1980s and 1990s would today be diagnosed as having autism. The research supports the theory that the rise in the number of cases of autism may be related to changes in how it is diagnosed.

Professor Dorothy Bishop, a Wellcome Trust Principal Research Fellow at the University of Oxford, led a study which revisited 38 adults, aged between 15-31, who had been diagnosed with having developmental language disorders as children rather than being autistic. Professor Bishop and colleagues looked at whether they now met current diagnostic criteria for autistic spectrum disorders, either through reports of their childhood behaviour or on the basis of their current behaviour. The results are published this month in the journal Developmental Medicine & Child Neurology(1).

Developmental language disorders, which include specific language impairment, are diagnosed when a child has unusual difficulty in his or her grasp of the spoken language, despite normal development in other areas. This may range from a child who has very limited ability to produce or understand spoken sentences, to one who does speak in long and complex utterances, but nevertheless has problem communicating effectively because of problems in conveying a point or grasping what others mean.

Autistic spectrum disorders, which include autism and Asperger syndrome, are developmental disorders affecting how a person communicates with and relates to other people and how they make sense of the world around them.

Participants in the study were drawn from a pool of children who had participated in a series of studies of developmental language disorder conducted during the period 1986 to 2003 and about whose conditions detailed information was known. All attended special schools or classes for children with language impairments, and would have been diagnosed by educational psychologists, paediatricians or speech therapists as having developmental language disorders and none had previously been diagnosed as autistic. However, when reassessed by Professor Bishop and colleagues using current criteria, around a quarter were identified as having autistic spectrum disorder.

In recent years, the criteria for diagnosing developmental language disorders and autism have changed. This has coincided with a marked rise in the rates of diagnosis of autism. According to the Special Needs and Autism Project(2), the figure until the 1990s was widely accepted as being about 5 people per 10,000; even using the narrowest definition of autism, this rose to almost 40 in 10,000 by 2006

There are two main hypotheses to explain this rise: the "autism epidemic" hypothesis and the "diagnostic substitution" hypothesis. Whilst the former says that the rise is genuine, the latter maintains that the true prevalence of the disorder is constant but that changes in diagnostic criteria mean that more children are being diagnosed as autistic. The latter theory is supported by a UK study(3) using the General Practice Research Database, which found that the rise in autism was mirrored by a decline in frequency of language disorders, and now by Professor Bishop's study.

"Our study shows pretty direct evidence to support the theory that changes in diagnosis may contribute towards the rise in autism," says Professor Bishop. "These were children that people were saying were not autistic in the 1980s, but when we talk to their parents now about what they were like as children, it's clear that they would be classified as autistic now.

"Criteria for diagnosing autism were much more stringent in the 1980s than nowadays and a child wouldn't be classed as autistic unless he or she was very severe. Now, children are being identified who have more subtle characteristics and who could in the past easily have been missed."

However, Professor Bishop cautions against using the results to suggest that the prevalence of autism is not genuinely rising.

"We can't say that genuine cases of autism are not on the increase as the numbers in our study are very small," she says. "However, this is the only study to date where direct evidence has been found of people who would have had a different diagnosis today than they were given fifteen or twenty years ago."

This research was funded by the Wellcome Trust.

Journal references:

1. Bishop D et al. Autism and diagnostic substitution: Evidence from a study of adults with a history of developmental language disorder. Developmental Medicine and Child Neurology, published in advance online 31 March 2008.

2. Baird G et al. Prevalence of disorders of the autism spectrum in a population cohort of children in South Thames: the Special Needs and Autism Project (SNAP). Lancet 2006; 368 (9531): 210-215.

3. Jick H et al. (2003) Epidemiology and possible causes of autism. Pharmacotherapy; 23: 1524-1530.


Story Source:

The above story is based on materials provided by Wellcome Trust. Note: Materials may be edited for content and length.


Cite This Page:

Wellcome Trust. "Rise In Autism Is Related To Changes In Diagnosis, New Study Suggests." ScienceDaily. ScienceDaily, 9 April 2008. <www.sciencedaily.com/releases/2008/04/080408112107.htm>.
Wellcome Trust. (2008, April 9). Rise In Autism Is Related To Changes In Diagnosis, New Study Suggests. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2008/04/080408112107.htm
Wellcome Trust. "Rise In Autism Is Related To Changes In Diagnosis, New Study Suggests." ScienceDaily. www.sciencedaily.com/releases/2008/04/080408112107.htm (accessed July 31, 2014).

Share This




More Mind & Brain News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Dieting At A Young Age Might Lead To Harmful Health Habits

Dieting At A Young Age Might Lead To Harmful Health Habits

Newsy (July 30, 2014) Researchers say women who diet at a young age are at greater risk of developing harmful health habits, including eating disorders and alcohol abuse. Video provided by Newsy
Powered by NewsLook.com
It's Not Just Facebook: OKCupid Experiments With Users Too

It's Not Just Facebook: OKCupid Experiments With Users Too

Newsy (July 29, 2014) If you've been looking for love online, there's a chance somebody has been looking at how you're looking. Video provided by Newsy
Powered by NewsLook.com
How Your Face Can Leave A Good Or Bad First Impression

How Your Face Can Leave A Good Or Bad First Impression

Newsy (July 29, 2014) Researchers have found certain facial features can make us seem more attractive or trustworthy. Video provided by Newsy
Powered by NewsLook.com
Losing Sleep Leaves You Vulnerable To 'False Memories'

Losing Sleep Leaves You Vulnerable To 'False Memories'

Newsy (July 27, 2014) A new study shows sleep deprivation can make it harder for people to remember specific details of an event. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



      Save/Print:
      Share:

      Free Subscriptions


      Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

      Get Social & Mobile


      Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

      Have Feedback?


      Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
      Mobile: iPhone Android Web
      Follow: Facebook Twitter Google+
      Subscribe: RSS Feeds Email Newsletters
      Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins