Genes, brain development, the dopamine and noradrenaline machinery, treatment trials — and the open questions still being argued.
1 · Start here
The evidence pages are ordered as a ladder: start with the overview, then climb down a level at a time — genes, development, the synapse, treatment trials — until you reach the questions nobody has answered yet. Each level states what is established, what is an association in groups, and what is still a hypothesis.
ADHD and biology — the overview — ADHD is supported by converging genetic, developmental, brain and treatment evidence. There is no single cause and no diagnostic brain or gene test — but the core machinery is well understood.
Genetics — many small influences — ADHD is highly heritable, but through thousands of common variants of tiny effect plus rarer variants in some families. Genes describe risk in populations, not a diagnosis in a person.
Brain development and structure — On average, the brain in ADHD matures on a later timetable, especially in prefrontal regions, with small differences in some deeper structures — largest in childhood.
The dopamine and noradrenaline supply chain — Six steps — make, store, release, clear, break down, self-tune. Simple parts; the complexity is in regulation, timing and how the steps interact.
No single dopamine story — Different studies point to different parts of the system, and some findings depend on medication history. ADHD is better described as several routes to a similar set of difficulties.
What treatment trials show — Randomised trials show the medicines reduce core symptoms in adults; a withdrawal trial shows frequent symptom relapse in previously stable adult lisdexamfetamine responders after switching to placebo. Registries suggest wider outcomes may improve, with important caveats.
Open research questions — Five live questions arising from one person's observations — each with competing explanations and the observations that would tell them apart. Questions, not conclusions, and never a reason to self-experiment.
Dystonia: patterned twisting and spasms — Dystonia is a movement disorder involving involuntary muscle contractions. This page helps you describe a pattern for assessment; a twisting sensation alone does not establish the diagnosis.
Coordination and balance: understanding ataxia — Ataxia describes impaired coordination. A description of imbalance is a starting point for assessment, not proof of one inherited or degenerative condition.
Dopamine-responsive dystonia: a distinct clinical question — Dopa-responsive dystonia is a specific group of movement disorders. Improvement with an ADHD medicine is not equivalent to the clinical levodopa response used in its assessment.
A field guide to the nervous system — Start with the affected function, the clinical pattern and the decision you need. Follow the evidence beyond slogans about a single chemical.
Parkinson’s: symptoms, treatment, genetics and care — A practical guide to recognition, motor and non-motor symptoms, treatment choices, medication continuity, genetics and research, with sources and questions to take to a specialist.
FND: diagnosis, active treatment and accountable care — Real symptoms deserve a positive diagnosis, symptom-specific rehabilitation, accessible support and a reviewed plan. Understand the options and what the treatment trials actually show.