Comment by usernametaken29
7 hours ago
I spent a decent amount working on ADHD diagnostics and unfortunately it sucks. To my knowledge, to this day, there isn’t a single reliable biomarker that identifies autism spectrum disorders. It’s usually correlation studies paired with questionnaires which for lack of better words can be described as “incidental” at best. Most z scored tests I know are also developed with small samples, a hundred participants with an outgroup of 20 would already be a LARGE sample. The standard ADHD questionnaire was validated on some 35 people.
There might be some hope in deep learning, particularly in observing eye movement components to deliver reliable biomarkers in the future, but I’m not so confident any time soon.
It’s dreadful and fascinating at the same time that defining and testing for ADS has been so elusive for so long…
From a molecular neuroscience perspective, for both ADHD and ASD (autism) you're unlikely to find any pure biomarkers as clean as a disease like huntingtons disease whose mechanism is clearly understood as extra CAG repeats on the HTT gene (a clean mendelian disorder). ADHD is defined by behavior/cognitive symptoms and most all behavior/cognitive diseases are multifactoral, which ADHD is. WES/WGS and GWAS has been done and for familial ADHD and unlike ASD there is mostly no clear monogenic mutation (a single gene that would explain the phenotype) [note monogenic mutations are usually a very small subset of cases but give scientists a look into what pathway/mechanism is causing a multifactoral disease]. Thus it is not for a lack of looking classically, and deficit is speculated to likely manifest as a neural circuit organization or synaptic issue (though the latter is more closely linked to ASD). This is currently impossible (basically) to measure in alive human brain as it requires nanoscopic imaging, note how challenging the fly map was (incomplete IMO as well).
ADHD also evolutionary advantages, so there is unlikely to be a single gene that encodes for it.
Evo-psych is impossible to falsify.
What are they? Are there papers on this?
1 reply →
1. How is it advantageous?
2. Assuming it really is: Why would this make it unlikely to be encoded on a single gene? As a layman, the only condition I'm aware of with this "downside but also upside" quality is sickle cell anaemia (downside is anaemia, upside is increased resistance to malaria), which is decided by a single nucleotide change on chromosome 11.
Isn't this true of nearly all mental disorders in DSM-5 and ICD-11?
We don't really know what mental disorders are and so we don't have objective diagnostic tests for them. [1]
We just have treatments that sometimes work for some people (and with the replication crisis[2] that sometimes is probably a lower value than expected).
[1] https://pmc.ncbi.nlm.nih.gov/articles/PMC6732705/
[2] https://pmc.ncbi.nlm.nih.gov/articles/PMC5835722/
ADHD is not an autism spectrum disorder, is it?
That’s my bad for conflating the two. Indeed they are not the same in ICT-11 but! diagnostics is moving towards the direction of treating them the same. ADHD and ASD have extremely high comorbidity and it has been proposed many times to classify them together because the symptoms overlap (difficulties at school, aggressive behaviour or temper, lack of social skills, etc). In fact it has become so difficult to find distinctive features of ADHD both in diagnostics AND treatment (both are usually treated with cognitive behavioural therapy and in more severe cases medication) that it has been proposed numerous times to drop their distinction in the ICT, but this hasn’t happened yet. Good paper to the point:
https://pmc.ncbi.nlm.nih.gov/articles/PMC4654237/
Autism Disorder with High Distractability?
I believe AuDHD is the common term.
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No, however they are often comorbid.