13 May 2019

Autism Diagnosis Stable By Fourteen Months Of Age

The findings suggest that an ASD diagnosis becomes stable starting at 14 months of age and overall is more stable than other diagnostic categories, including language or developmental delay.
From here (citing this article in JAMA Pediatrics). The abstract from the referenced article is as follows:
Importance Universal early screening for autism spectrum disorder (ASD) in primary care is becoming increasingly common and is believed to be a pivotal step toward early treatment. However, the diagnostic stability of ASD in large cohorts from the general population, particularly in those younger than 18 months, is unknown. Changes in the phenotypic expression of ASD across early development compared with toddlers with other delays are also unknown. 
Objectives To examine the diagnostic stability of ASD in a large cohort of toddlers starting at 12 months of age and to compare this stability with that of toddlers with other disorders, such as developmental delay. 
Design, Setting, and Participants In this prospective cohort study performed from January 1, 2006, to December 31, 2018, a total of 2241 toddlers were referred from the general population through a universal screening program in primary care or community referral. Eligible toddlers received their first diagnostic evaluation between 12 and 36 months of age and had at least 1 subsequent evaluation. 
Exposures Diagnosis was denoted after each evaluation visit as ASD, ASD features, language delay, developmental delay, other developmental issue, typical sibling of an ASD proband, or typical development. 
Main Outcomes and Measures Diagnostic stability coefficients were calculated within 2-month age bands, and logistic regression models were used to explore the associations of sex, age, diagnosis at first visit, and interval between first and last diagnosis with stability. Toddlers with a non-ASD diagnosis at their first visit diagnosed with ASD at their last were designated as having late-identified ASD. 
Results Among the 1269 toddlers included in the study (918 [72.3%] male; median age at first evaluation, 17.6 months [interquartile range, 14.0-24.4 months]; median age at final evaluation, 36.2 months [interquartile range, 33.4-40.9 months]), the overall diagnostic stability for ASD was 0.84 (95% CI, 0.80-0.87), which was higher than any other diagnostic group. Only 7 toddlers (1.8%) initially considered to have ASD transitioned into a final diagnosis of typical development. Diagnostic stability of ASD within the youngest age band (12-13 months) was lowest at 0.50 (95% CI, 0.32-0.69) but increased to 0.79 by 14 months and 0.83 by 16 months (age bands of 12 vs 14 and 16 years; odds ratio, 4.25; 95% CI, 1.59-11.74). A total of 105 toddlers (23.8%) were not designated as having ASD at their first visit but were identified at a later visit. 
Conclusions and Relevance The findings suggest that an ASD diagnosis becomes stable starting at 14 months of age and overall is more stable than other diagnostic categories, including language or developmental delay. After a toddler is identified as having ASD, there may be a low chance that he or she will test within typical levels at 3 years of age. This finding opens the opportunity to test the impact of very early-age treatment of ASD.
There is no rigorously evidence validated treatment of autism at any age, although there are approaches which are used to manage the symptoms. Also, it is worth noting that autism is a syndrome of similar symptoms that tend to appear together but almost certainly has multiple distinct causes (mostly de novo genetic mutations) that all affect the same neurological sub-systems of the body in similar ways. 

So, a cure to one cause of autism wouldn't necessarily be a cure to most cases of autism. 


neo said...

what do you think is the relation between autism and intelligence, and why asperger's presents so differently from low functioning autism

andrew said...

Severe autism is usually associated with low IQ to the point of developmental disability. Less severe autism is associated with only modest deficits in IQ. The mildest forms of the autism spectrum (previously called Asperger's Syndrome) don't appear to suppress intelligence at all, outside fairly specific functional areas. I don't think that anything on the autism spectrum truly increases intelligence, although I do think that it may specialize available IQ capacity by interfering with other ways that IQ capacity could be developed, leading stereotypically, to someone who over performs relative to their overall IQ in STEM type thinking and underperforms relative to their overall IQ in language and interpersonal interaction tied uses of IQ relative to their overall IQ.

Everything on the autism spectrum is targeting some general subset of the nervous system including the brain. The more fully that system has been defeated, the more it interferes with overall cognition. The less completely that system has been impaired, the more it is possible for the brain to "work around" autism to carry on other forms of cognition.

It is possible to have meaningfully above average IQ while still being on the autism spectrum, because the functions we associate with IQ are predominantly those involving the 'higher brain" or "primate brain" such as the frontal cortex, while the functions we think of as diagnostic of and a litmus test of the autism spectrum are those associated with the "mammalian brain" such as empathy and understanding of other people, even though in truth the brain is too complete to neatly partition those functions.

neo said...

some parents with children with both, and feel it's 2 separate things going on.

there are books and researchers who speculate that many historical geniuses like einstein and newton on are the spectrum, and many current physicists and programmers have come out of the closet as being on the spectrum.

i think if this kind of research was done into personality disorders, esp anti-social personality, instead of calling them personality disorders they should be considered developmental disorders.