Is Lactic Acid the Missing Link in ADHD and Stimming?

When most people hear “ADHD,” they think of hyperactivity, distractibility, or trouble focusing. But what if the underlying challenge wasn’t just about attention — but about energy?

Recent research is shining light on an unexpected player in the ADHD puzzle: lactic acid, a molecule typically known for its role in muscle fatigue. In the brain, however, lactic acid acts not as a waste product but as a vital fuel, and disruptions in how the brain accesses this fuel may explain some of the core struggles faced by individuals with ADHD.

The Brain’s Hidden Fuel: What is Lactic Acid Doing Up There?

Lactic acid, or more specifically lactate, is produced in the brain by support cells called astrocytes. These cells help deliver lactate to neurons as an energy source, particularly in times of high mental demand. This process — known as the astrocyte–neuron lactate shuttle — helps power cognitive tasks like focus, memory, and emotional regulation.

In people with ADHD, scientists have proposed that this energy delivery system may be impaired. The result? A brain that tires easily and struggles to maintain sustained attention, not due to lack of motivation, but due to metabolic fatigue.

A 2013 review in Neuroscience & Biobehavioral Reviews suggested that the effectiveness of stimulant medications (such as methylphenidate, commonly known as Ritalin) might partially come from their ability to increase lactate availability in the brain — boosting energy levels for neurons that are otherwise underpowered (Magistretti & Allaman, 2013).

Rethinking Stimming: From Distraction to Adaptation

The link between energy and attention also helps explain a commonly misunderstood behaviour in ADHD: stimming.

Short for "self-stimulatory behaviour," stimming includes repetitive movements or actions like foot-tapping, pen-clicking, pacing, or hand-flapping. While often associated with autism, stimming is increasingly recognised in people with ADHD as a natural self-regulation strategy.

Rather than being a distraction or bad habit, stimming may help compensate for reduced brain energy. By providing physical stimulation, individuals may be subconsciously boosting alertness and improving focus. In this context, stimming isn't a symptom to be stopped — it's an intelligent, adaptive behaviour.

As Verywell Health notes, “Stimming helps people with ADHD regulate their emotions, focus their attention, or manage sensory overload” (Verywell Health, 2023).

The Gut-Brain Connection: Another Piece of the Puzzle

Adding to this complex picture is the gut-brain axis — the bidirectional communication between the digestive system and the brain. Our gut microbiota plays a key role in producing or influencing the availability of lactic acid.

Disruptions in gut health, inflammation, or diet may therefore affect the brain's energy balance and, by extension, contribute to symptoms of ADHD.

A 2021 review published in Nutrients emphasized the role of gut bacteria in ADHD and suggested that microbiome-based interventions may one day complement traditional treatments (Wang, Yang & Bai, 2021).

What This Means for Support and Understanding

Understanding ADHD through the lens of energy metabolism offers a more compassionate and practical approach to support.

• Movement breaks can be reframed not as distractions but as energy resets.

• Nutrition and gut health become essential tools in managing cognitive function.

• Stimming behaviours deserve to be respected as signs of self-regulation, not dismissed as disruptive.

• And education and workplace accommodations can focus on reducing cognitive overload, rather than simply demanding more effort.

This perspective shifts ADHD away from a deficit of attention or discipline and toward a nuanced understanding of brain energy — and how best to fuel it.

References

• Magistretti, P.J. and Allaman, I., 2013. Lactate in the brain: from metabolic end-product to signalling molecule. The Neuroscientist, 21(2), pp.136–145. Available at: https://www.sciencedirect.com/science/article/abs/pii/S014976341300047X .

• Verywell Health, 2023. What is Stimming and How Is it Related to ADHD? Available at: https://www.verywellhealth.com/adhd-stimming-5208900 .

• Wang, L.J., Yang, C.Y. and Bai, Y.M., 2021. The role of gut microbiota in ADHD: A literature review. Nutrients, 13(1), p.249. Available at: https://www.mdpi.com/2072-6643/13/1/249 .