Comment by timster6442 | Hacker News Reader

Comment by timster6442 | Hacker News Reader

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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).

There’s a doctor who goes by Russell Barkley, PhD on his popular YouTube channel and claims to be able to brainscan for ADHD with certainty. Is his claim legitimate?

Russel Barkley is a pioneer in the field of ADHD research. I have heard of such a claim, but not from Russel Barkley. Could you provide a link of Russel Barkley making the claim please?

It's somewhere in this talk (broken down as a playlist). It's been a while since I've watched it but I do recall him saying that they can see physically differences in the brain of adhd folks

https://www.youtube.com/watch?v=BzhbAK1pdPM&list=PLzBixSjmbc...

Seeing physical differences in brain volume, connectivity or activity between groups of many adhd folks and non-adhd folks is one thing and that can be done. However, performing a clinical diagnosis of adhd in an individual, solely based on a brain scan, is a completely different thing.

He's a legit researcher though I haven't seen his work on youtube. In terms of how accurate brain scans are at diagnosing adhd you can look at recent meta analyses (gold standard of evidence based medicine pyramid).

In a 2024 meta-analysis of MRI/fMRI machine-learning studies for ADHD, the average pooled sensitivity was 74% (the ability to correctly identify people who actually have ADHD) and the average pooled specificity was 75% (the ability to correctly identify people who do not have ADHD), that also means that there is a 26% false-negative rate (miss/Type II error) and a 25% false-positive rate (accidental diagnosis/Type I error) [https://doi.org/10.1016/j.jad.2024.03.111].

Though there is no set standards but under 80% is pretty low for a clinically useful test but can still be used in some conditions such as to supplement diagnosis. To give some numbers the rapid antigen covid tests had 72% sensitivity and 98.9% specificity. (note the lower sensitivity was acceptable at the time but the CDC guideline was for symptomatic people to retest 48 hours. Viral load and other staging factors could all confound.) [https://doi.org/10.1371/journal.pmed.1004011]

If I remember correctly there are some paradigms in which you can show it in fMRI quite clearly but the trouble is of course MRIs are not accessible to a wide public. I will have to go dig through papers though, I have not read into MRI based diagnostics in a long while

ADHD also evolutionary advantages, so there is unlikely to be a single gene that encodes for it.

What are they? Are there papers on this?

There are only papers which suggest this could be true, none that conclusively prove it. That I’m aware of.

There are some cool studies done where people with a without ADHD are tasked to forage berries. The people with ADHD do better and adhere to foraging patterns which existing theories suggest would be more optimal.

A lot of the studies like that indicate the individual with the condition might benefit more from ADHD than the group they’re in, but I’m not sure that studies have explored group benefits very much.

There’s an often cited paper in which nomadic men who carry a certain ADHD-related allele (DRD4-7R, a dopamine reception variant with ADHD traits and novelty seeking) tend to have better nutritional status. I can’t recall much about it or how high quality it is.

I’ve always thought, it’s not absurd to think there different development routes which the brain takes depending on the environment it develops in.

With your foraging example, it does make me think ADHD is a small group/individual optimisation. Prioritising high vigilance and individual productivity over social cohesion.

I speak with no authority. I don’t even know how such a theory could be tested.

> I’ve always thought, it’s not absurd to think there different development routes which the brain takes depending on the environment it develops in.

What do you think nutritional stunting means?

https://en.wikipedia.org/wiki/Stunted_growth

I don’t mean from a nutritional standpoint, but a behavioural perspective. Smaller groups would have an higher percentage of responsibility per individual to be vigilant and proactive.

It would make sense to me that evolutionary there would be different mental development paths depending on the requirements of their situation.

This is coming from my understanding that ADHD is more prevalent in stressful upbringings.

If adhd is heritable, then the stressful upbringing could be symptomatic of the parent's condition instead of causal.

I agree, stress during pregnancy could also be a signal shared with the developing brain.

> I don’t mean from a nutritional standpoint, but a behavioural perspective.

That would normally be called "learning". Also a pretty conventional idea.

With learning, though, you'd want to explain why something becomes immune to further learning at a certain point.

Not necessarily. ADHD is at the neurotransmitter level or density of receptors. Which could be an epigenetic condition from prenatal environment.

Or maybe it’s learnt like you say, I think both areas would be worthy of researching.

I don't know about papers but I had a doctor tell me they are overrepresented among snipers in the military. ADD could be an advantage to hunting.

Or ADD just sucks there less than in other areas.

Like being physically weak is not an advantage in white collar jobs.

ChatGPT's take was that 10 ADHD people/animals would go exploring and if one produced a new source of food then it would be advantageous for the group, but the other 9 could fail and be completely useless. A bit like venture capital funds haha.

So there is still room for complete failure in life, and maybe its a lot of luck/environment that some ADHD people succeed naturally.

A psychiatrist told me that people with ADHD perform better under extreme pressure and chaos. No idea if that's true. Personally I don't even think of ADHD as a deficiency. It's just a trait that is not compatible with modern society and workplace.

There might be a correlation, but I doubt causation. I would argue people with ADHD, like myself, tend to end up in situations where extreme pressure and chaos is more common. Thus, we have more exposure than the average person. I imagine it can be a trainable trait in many people.

Yeah, I think this is the key point. I am better at handling chaos because I grew up around chaos (my mom has adhd and so do I) so I am much better at handling things falling apart.

A common meme you'll see on ADHD in online posts are about how people with it are perfectly calm during emergencies, but then when any inconsequential thing happens such as e.g. breaking a shoelace and they'll just unravel and/or take forever to deal with it.

Evo-psych is impossible to falsify.

I wish everyone would get this!

Practically all statement outside of mathematics is a soft statement.

IMO "Humans do this because [made up scenarios how it helped them survive]" is trash in its own rights, and not because it is not falsifiable. Not useful, not insightful, not anything.

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.

> As a layman, the only condition I'm aware of with this "downside but also upside" quality is sickle cell anaemia

Essentially all traits that you might think of as "traits" and not "features of the species" have downsides and also upsides. Where there's any significant imbalance, the genes for that trait will be purged from the gene pool (if the trait is basically all negatives) or sweep to become universal (if all positives).

By seeking out novelty, someone could be a more effective forager or better able to spot predators/prey hiding. ADHD often comes with a high attention to detail, so there's lots of advantages that could come with that (e.g. that twig wasn't broken before, something has passed through here).

Also, having different sleeping patterns can mean that the people with ADHD are likely better equipped to keep a fire burning overnight and possibly be alert for predators.

> ADHD often comes with a high attention to detail

Per the DSM-5, one of the core symptoms of ADHD:

"often fails to give close attention to details or makes careless mistakes in schoolwork, work, or other activities

Yes, it's both a lack of attention to details in "boring" tasks and an exceptional attention to details in "interesting" tasks.

I think there is a conflation between attention and attention to details. I understand attention control can vary depending on the engagement value of a task. I have experienced the condition my entire life, I am well aware.

I am not aware of any data that supports being interested in a task lessens the likelihood of making mistakes. If you have any data, I will gladly read it.

This isn't funny

Sometimes the upside is just being different. I heard about a group of cattle, and one of them was ill, while the others feasted. The feed was tainted, and so only the sick one survived.

Though, with ADHD, I think it's definitely more than that. It doesn't just make it hard to focus, it makes it hard to focus on what you need to, until the moment that it is obviously now or never. Focus, though - there's tons of that, flitting about, and sometimes grabbing you up and running away with you - sometimes for months. I would imagine that there are a lot of novel discoveries attributable to it.

Am biologist and keeping genes that are "advantageous" is the most common trap that people fall into about evolution. Evolution isint actually about keep advantageous traits the real idea is about differences in reproductive success, not about evolution systematically preserving only traits that are beneficial to the individual.

In fact Darwin's theory of evolution is kind of outdated as well. We now understand genetic drift and things like the neutral theory of molecular evolution from moto kimura and the nearly neutral theory of evolution from tomoko ohta may give some sort of explanation to polygenic nature of adhd.

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