Guide to ADHD Neurobiology and Brain Networks
The brain foundations of ADHD: dopamine, brain networks (DMN/TPN), and genetic heritage.
Neurobiological Foundations and Dopamine
ADHD is not just a simple 'dopamine deficiency,' but a dysregulation of dopamine and norepinephrine dynamics within the 'Catecholamine Hypothesis.' When dopamine signaling in the prefrontal cortex decreases; executive functions such as attention, planning, and impulse control are seriously disrupted.
According to Assoc. Prof. Dr. Aslı Kazgan, supplements such as Phosphatidylserine and Citicoline during this process can optimize synaptic transmission speed by protecting neuronal membrane integrity and supporting the acetylcholine cycle. These substances allow the message traffic between neurons to flow more smoothly.
Genetic studies show that ADHD is as heritable as height (74-90%). Especially variations in dopamine receptor and carrier genes such as DRD4 and SLC6A3 directly affect the brain's reward and alertness systems. This is the strongest evidence that ADHD is not a discipline problem, but a biological heritage.
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Conflict of Brain Networks: DMN vs. TPN
Resting-state fMRI (rsfMRI) studies show that the balance between the two major networks in the brain, the 'Default Mode Network' (DMN - daydreaming) and the 'Task Positive Network' (TPN - focusing), is disrupted. In a neurotypical brain, these networks are like a seesaw; when one opens, the other closes.
According to Nörofarklıyız and Otizm TV experts, brains in the ADHD/Autism spectrum have a 'Sensory Gating' problem. The brain cannot filter unimportant background noises (the sound of air conditioning, a tag scratching). This unfiltered data entry results in DMN always being over-stimulated and the mind being unable to maintain focus.
In an ADHD brain, the DMN refuses to shut down even during a task. This is a neural 'traffic control' problem that causes the mind to constantly shift to dreams or irrelevant thoughts (mind-wandering) while trying to focus on a job. The simultaneous activity of these two networks is the main source of mental fog and chaos.
@adhdwithbest defines this situation with a very striking metaphor: 'Having 50 tabs open in the mind at the same time and not being able to find where the music is coming from.' In women with ADHD without physical hyperactivity, this situation (Mental Hyperactivity) leads to severe exhaustion even if no bodily work is done at the end of the day.
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Executive Functions and Developmental Delay
According to Dr. Russell Barkley, ADHD is approximately a 30% developmental delay of the structural orchestra conductor in the prefrontal cortex. This region cannot apply brakes to emotion waves coming from the amygdala and struggles to give the neurochemical command to initiate action.
Executive functions cover working memory, impulse control, emotion regulation, and planning. This capacity being behind the biological age causes the individual to 'be unable to do' what they 'know they should do' (knowing-doing gap), independent of their intelligence.
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Perception of Danger: Is Every Task an Emergency?
According to clinical observations, the Amygdala (emotional alarm center) in the ADHD/AuDHD brain is hypersensitive. Due to the weakness of the prefrontal cortex (braking mechanism), even as simple as 'answering an email' or 'grocery shopping' can be perceived by the brain as a vital 'danger' or 'emergency.'
This situation leads to a chronic 'Fight or Flight' mode. The person is constantly on alert, which creates a feeling of physical exhaustion and unexplained tension at the end of the day. Having high justice sensitivity is also one of the factors triggering this alarm system.
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Sensory Processing and Bodily Cost
According to neuro-affirming analyses, sensory stimulation (sound, light, smell) in neurodivergent individuals does not just create 'discomfort' but an actual 'wear' in the nervous system. Because the brain cannot filter incoming data (filter deficit), the nervous system consumes enormous energy while trying to keep the arousal level in balance at all times.
This sensory overload (Sensory Overload) manifests itself not just mentally, but also with somatic (bodily) effects such as digestive problems, joint pains, and chronic fatigue. As stated by Konak Psikoloji (Sinem Çatalyürek Kesiktaş), sensory regulation is not just a relaxation method, but a vital biological requirement to protect the nervous system of the neurodivergent individual.
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DMN and TPN Balance: Cengiz Arca’s Approach
Psychiatrist Dr. Cengiz Arca defines network communication in the ADHD brain as an existential 'Unfilteredness.' While the classic medical approach sees the DMN (Default Mode Network) not shutting down during a task as a 'mistake,' Arca interprets this situation as the brain 'broadcasting on multiple channels at the same time.'
The incompatibility of these networks (hyperactivity of the DMN and weakness of the TPN) makes the contact the person establishes with the world much richer but also chaotic. According to Arca, instead of trying to silence the brain only with chemicals (medications), the first step should be to make peace with the broad-spectrum perception capacity brought by this unfilteredness and to structure it (phenomenological acceptance).