"ADHD brains are low on dopamine." You have probably read it a hundred times, usually right before someone sells you a supplement to "boost" it. A widely shared post now says a major scientific review found that this simple story does not hold up. We checked the review. The post is right, and the details are more interesting than the slogan it replaces.
The Real Review
The source is MacDonald, Kleppe, Szigetvari and Haavik (2024), researchers at the University of Bergen and Haukeland University Hospital in Norway, published in Frontiers in Psychiatry. They went through more than 40 years of evidence on dopamine and ADHD from four angles: genetics, rare metabolic diseases, brain imaging and animal models. Their conclusion, in their own words: there is "evidence for the involvement of dopamine but limited evidence for a hypo-dopaminergic state per se as a key component of ADHD."
One thing they point out early is telling: across decades of papers, there was never a clear consensus on what "the dopamine hypothesis" even meant. Less dopamine overall? Less in the prefrontal cortex? Weaker signaling? Slower metabolism? Different studies tested different things and called them all the same name.
Three Findings That Break the Slogan
- People who genuinely lack dopamine do not look like ADHD. Rare genetic diseases exist where the body cannot make or transport dopamine properly (dopamine transporter deficiency syndrome, defects in the enzymes that synthesize dopamine, DOPA-responsive dystonia). These patients develop severe movement disorders, involuntary movements, dystonia, developmental delay, "but not typical ADHD symptoms," the review notes. If ADHD were simply a dopamine shortage, these are the people who should have it most.
- Brain scans point in both directions. Summarizing the PET and SPECT imaging literature, the authors write that recent studies "do not show predominant evidence supporting a hypo-dopaminergic state in ADHD, but rather conflicting results that imply both increased and decreased" dopamine levels in the same brain regions. Part of the mess: stimulant medication itself changes the dopamine system, so who had been treated before scanning matters a great deal.
- The big genetic studies do not put dopamine genes on top. Early small studies of "candidate genes" like DAT1 and DRD4 got a lot of attention, but the review finds they "suffered from low power and inconsistent results." In the large genome-wide studies (tens of thousands of people), "core dopamine-related genes are not among the major risk genes for ADHD."
What This Does Not Mean
It does not mean dopamine is irrelevant. The same genome-wide data show that ADHD risk variants are enriched in genes expressed in midbrain dopamine neurons, and stimulant medications that act on dopamine and noradrenaline clearly help many people. Dopamine is part of the picture. What the evidence does not support is the idea of ADHD as a single-chemical shortage that you could measure with a blood test or fix with a pill or a powder. ADHD involves multiple brain networks and several neurotransmitter systems interacting, and probably looks different across subgroups of people who currently share one diagnosis.
Why It Matters for You
The "low dopamine" story is not just a simplification, it is a marketing hook. Supplements, protocols and "dopamine detox" routines are sold on it. If the underlying biology is not a shortage, a product promising to top you up is solving a problem the research cannot find. Understanding ADHD as a network-level difference, rather than a chemical deficit, also happens to be a kinder and more accurate way to understand yourself.
If attention, restlessness or impulsivity sound like you, start with something that has real validation behind it: our free ADHD screening test (ASRS-v1.1).
Sources: MacDonald HJ, Kleppe R, Szigetvari PD, Haavik J (2024). "The dopamine hypothesis for ADHD: An evaluation of evidence accumulated from human studies and animal models." Frontiers in Psychiatry, 15:1492126; Demontis D et al. (2023). "Genome-wide analyses of ADHD identify 27 risk loci." Nature Genetics 55:198-208.