Why does performance fluctuate so dramatically in ADHD? A Berlin researcher has a new answer

Many people with ADHD will recognise the pattern: hours of hyperfocus one moment, complete exhaustion at the next simple task. More and more people across Europe are receiving a diagnosis of attention deficit hyperactivity disorder (ADHD), with numbers rising particularly among women, even as understanding of the condition continues to improve. What remains unclear is why attention and performance fluctuate so markedly in those affected. A new study from Freie Universität at Brain City Berlin now offers a fresh explanation.

Mohammad Dawood Rahimi, a neurobiologist at FU Berlin, recently presented his model of "Energy Deficit Hyperactivity Disorder" (EDHD) in the prestigious journal Neuroscience & Biobehavioral Reviews. This approach reframes ADHD as a consequence of unstable neural energy availability. According to the model, people with ADHD do not fundamentally lack attention. Instead, they have an unstable, rapidly depleted mental energy. This dynamic could explain why those affected are able to work with intense concentration in some situations, whilst in others even simple tasks prove a struggle.

From attention deficit to energy regulation 

The framework is intended to contribute to the destigmatisation of those with the condition. "The model sheds new light on a disorder studied for decades," says Mohammad Dawood Rahimi from the Cognitive Neuroscience Division at Freie Universität Berlin. Phenomena such as hyperfocus or dramatic swings in performance can be better understood through the EDHD model.

A commonly described feature of ADHD is the extreme variability in performance: many people with ADHD can concentrate intensely for hours on highly engaging tasks, yet face considerable difficulty with monotonous or prolonged ones. The EDHD model explains this as a result of energy regulation: stimulating tasks momentarily optimise the brain's energy allocation, whilst mundane tasks deplete limited reserves without providing the "arousal feedback" needed to maintain metabolic supply. Performance capacity is therefore contingent on the energetic context of the task.

In his study, the researcher argues that neurobiological processes such as glucose metabolism and mitochondrial function could play a central role. Certain brain regions, including those responsible for planning, attention, and self-regulation, may at times receive insufficient energy. Rahimi is also clear that: "EDHD is a theoretical framework, not a clinical diagnostic tool. The objective is to synthesise findings from neuroscience, mitochondrial biology, and computer modelling into a systemic framework that explains these neuro-energetic phenomena."

Rest and structure as key factors 

Within the EDHD model, stable attention depends above all on sufficient recovery. Sleep, breaks, and biological rhythms determine how much cognitive energy is available. Without this regeneration, even simple tasks can become overwhelming – a possible explanation for the typical fluctuations in performance.

Behaviours such as restlessness or distractibility also appear in a different light through this framework: they could be compensatory strategies to stimulate arousal and stabilise energy levels. Movement or new stimuli help the brain to maintain its capacity. This shifts the understanding of ADHD away from questions of discipline and towards the management of biological resources. In practical terms, new avenues open up, such as a greater focus on sleep, nutrition, and metabolism alongside medication. The EDHD model is a step in this direction, and Brain City Berlin, with its strong neuroscience community, is likely to play an important role in taking it forward.

Further information 

• The study: Rahimi, M. D. (2026). "Energy Deficit Hyperactivity Disorder (EDHD): A Neurobiological Energy Dysregulation Model for ADHD", published in Neuroscience & Biobehavioral Reviews, is available at: https://doi.org/10.1016/j.neubiorev.2026.106616 
• Press release from FU Berlin: https://www.fu-berlin.de/en/presse/informationen/fup/2026/fup_26_051-ADHS-Erklaeransatz-EDHD-neuroscience/index.html 
• Mohammad Dawood Rahimi, Freie Universität Berlin, Department of Education and Psychology, Cognitive Neuroscience Division, Email: rahim84@zedat.fu-berlin.de