u/NormalAd8171

I've been researching attention networks lately and noticed something interesting. Several of you reading this might have thought that CDS and ADHD sometimes look like the total opposites of each other, some believe it actually is the case. Well, there might be SOME truth to this claim.

Everyone knows executive dysfunction is at the heart of ADHD. Executive dysfunction is heavily interchangeable, in my opinion, with 'problems in top-down attentional processing'. Top-down refers to going from executive to operational, while bottom-up refers to going from operational to executive. In economics, top-down means going from big picture (plans, strategy) to specific details, while bottom-up means going from data and details to strategy and big picture.

In terms of attentional processing, I think the best way to describe top-down and bottom-up is top-down meaning you consciously directing your attention towards something and sustaining that attention (sending stimuli), while bottom-up means receiving stimuli and unconsciously directing your attention towards that (receiving stimuli.)

Defining top-down attentional processing that way does explain executive dysfunction more mechanically. Now, the brain network responsible for top-down attention is the Dorsal Attention Network, and expectedly, there is atypical connectivity within this region in people with ADHD.

The brain network responsible for bottom-up attention is the Ventral Attention Network. Guess what? There is atypical connectivity within this region in people with CDS (https://www.sciencedirect.com/science/article/pii/S2949732924000668). You could say that ADHD is problems with top-down attentional processing, while CDS is problems with bottom-up attentional processing. Ngl this fact was kind of known in other terms. I already knew that CDS had more to do with 'attentional orientation' issues but looking at both disorders in attentional processing terms is pretty interesting. You could say that ADHD and CDS are two sides of the same coin.

The Salience Network is network in the brain that filters out salient (important, relevant) stimuli and allocates the necessary attention and resources to process said stimuli. For example, when a fire alarm goes off, the salient network attributes salience to that sound and directs your attention from whatever you were doing now to the danger in this new situation. The salient network also acts as a switch between the DMN (Default Mode Network) and CEN (Central Executive Network)

The DMN (also called the Task Negative Network)  is active when you are at rest or not doing a task. This is when you daydream the most and are reflecting internally.

The CEN is part of the TPN (Task Positive Network) and is active when not at rest and during a complex task. The DMN and CEN are anticorrelated, meaning when one is more active, the other one is equally inactive. The CEN is underactive in people with CDS.

It has been shown that in people with ADHD, the anticorrelation between the DMN and CEN is decreased, which supports the hypothesis of DMN interference when CEN is active, causing distraction and impaired focus (https://cambridgeadhdclinic.com/triple-network-model-neurocognitive-insights-adult-adhd/#:\~:text=The%20triple%2Dnetwork%20model%20is%20a%20modern%20neurocognitive,Detects%20important%20stimuli%20and%20drives%20network%20switching). The functional connectivity within the CEN itself is also lower in people with ADHD, which is of course correlated with executive dysfunction.

It is well known that the DMN is overactive in CDS, but research is still limited when it comes to CDS’ relation to the Triple Network Model. An interesting detail is that there is a higher functional connectivity between the DMN and Dorsal Attention Network (Focus on goals and external cues, inhibit distractions) in ADHD, while a higher functional connectivity between the DMN and Ventral Attention Network (attention orientation, reorient focus to unexpected and salient stimuli) is associated with CDS. (https://www.sciencedirect.com/science/article/pii/S2949732924000668). 

I interpret this as people with CDS have a hard time getting out of their DMN. In my experience, I wouldn’t say my DMN is interfering when I’m doing a task, more so that my DMN is constantly active which makes everything else vague. What I'm saying is that maybe there is no reduced anticorrelation between the DMN and CEN, like we see in ADHD, which would mean that the CEN is just too underactive in people with CDS. This would mean that my Salience Network just cannot properly switch, ever. Maybe that’s the cause of our symptoms. Or maybe the energy it takes to switch between DMN and CEN is excessive, which explains the fatigue or something. Wish they could research the difference in SN between ADHD and CDS.

Thoughts?