ADHD, Perimenopause and the Three Brain Chemicals Nobody Explained to You: Dopamine, Serotonin and Noradrenaline

If you've ever wondered why perimenopause didn't just bring hot flushes and irregular periods but took with it your focus, your mood, your motivation, and your ability to feel anything resembling calm, this is the explanation you weren't given.

It comes down to three neurotransmitters. And oestrogen was supporting all of them. 

Dopamine

Dopamine is the brain's reward and motivation chemical. It's what fires when something feels interesting, urgent, or worth doing. It's what drives you to start things, finish things, and feel satisfied when you do.

ADHD is, at its core, a dopamine dysregulation condition. The ADHD brain doesn't produce or process dopamine the same way a neurotypical brain does. That's why tasks that aren't immediately interesting or rewarding are so hard to start or complete. That's why the ADHD brain seeks novelty, urgency, and stimulation. It's chasing the dopamine it isn't getting through ordinary daily life.

Oestrogen directly supports dopamine synthesis and receptor sensitivity in the prefrontal cortex, the area of the brain responsible for focus, planning, impulse control, and decision-making. It's also the exact area ADHD already struggles with most. Testosterone also contributes here. It supports dopamine function alongside energy, motivation, and cognitive drive. Its decline in perimenopause adds to the motivational flatness that women with ADHD describe as particularly hard to push through.

For women with ADHD, oestrogen and testosterone have been providing partial support to a dopamine system that was already running low. When both decline in perimenopause, that support disappears. The gap between what the brain needs and what it's getting widens. Tasks that were manageable become harder. Motivation drops further. The strategies that worked for years stop working almost overnight (Kooij et al., 2025).

Serotonin

Serotonin is involved in mood regulation, sleep, appetite, and emotional resilience. When serotonin is working well, you can absorb a difficult day without falling apart. When it isn't, everything hits harder.

Oestrogen supports serotonin production and enhances the sensitivity of serotonin receptors throughout the brain. This is why many women notice that their mood is more stable in the first half of their cycle when oestrogen is higher, and less stable in the second half, or luteal phase, of their cycle, when it drops.

In perimenopause, as oestrogen declines, serotonin function decreases with it. Low mood, heightened anxiety, poor sleep, increased emotional reactivity, and a sense of flatness or disconnection are all consistent with reduced serotonin activity. For women with ADHD, who were already more prone to emotional dysregulation, this compounds something that was already difficult to manage (Barth, Villringer and Sacher, 2015).

This is also why so many women in perimenopause are diagnosed with depression or anxiety before anyone looks at their hormones. The symptoms overlap significantly. The distinction matters because treating serotonin deficiency with an antidepressant when the underlying driver is falling oestrogen is, at best, addressing the symptom and not the cause.

Noradrenaline

Noradrenaline, also called norepinephrine, is the brain's alertness and attention chemical. It supports focus, working memory, and the ability to filter out irrelevant information. It's also involved in the stress response alongside cortisol.

ADHD medications like atomoxetine work specifically on the noradrenaline system because it plays such a central role in attention regulation. The ADHD brain has dysregulated noradrenaline activity as well as dopamine, which is part of why focus and working memory are so affected.

Oestrogen supports noradrenaline function too. As it declines in perimenopause, the noradrenaline system becomes less efficient. Working memory worsens. The ability to hold information in mind and use it deteriorates. The brain becomes harder to regulate and easier to overwhelm. Women describe this as a brain fog that feels qualitatively different from ordinary tiredness, and they're right. It is (Kooij et al., 2025).

Why All Three Together Explain So Much

Dopamine, serotonin, and noradrenaline don't work in isolation. They interact constantly. When one is dysregulated, the others are affected. In ADHD, all three systems were already compromised to varying degrees. Oestrogen was providing support across all three. Testosterone was contributing to dopamine and motivational function. 

Progesterone's main role for the ADHD brain is via the GABA and HPA axis pathway, which you can read about in full here.

When oestrogen and testosterone decline, the support is withdrawn from multiple systems simultaneously. This is why perimenopause doesn't just feel like a gradual worsening. For women with ADHD, it can feel like a sudden collapse of everything that was holding them together. Because neurologically, that's exactly what it is.

What This Means Practically

HRT that restores oestrogen can help support all three neurotransmitter systems, not just relieve hot flushes. This is why, for many women with ADHD, oestrogen replacement is transformative rather than merely helpful. ADHD medication may also need reviewing in perimenopause, not because of tolerance, but because the hormonal environment it's working in has changed. And sleep, which is disrupted by both low serotonin and low oestrogen, is worth prioritising with the same seriousness as any other treatment.

None of this is about trying harder or thinking more positively. It's about three brain chemicals, the hormones that were supporting them, and what happens when that support is taken away.

You weren't imagining it. Your brain's neuro-chemistry changed. 

References

Barth, C., Villringer, A. and Sacher, J. (2015) 'Sex hormones affect neurotransmitters and shape the adult female brain during hormonal transition periods', Frontiers in Neuroscience, 9, p.37. Available at: https://doi.org/10.3389/fnins.2015.00037

Kooij, J.J.S. et al. (2025) 'Research advances and future directions in female ADHD: the lifelong interplay of hormonal fluctuations with mood, cognition, and disease', Frontiers in Global Women's Health, 6, article 1613628. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC12277363/

Sharma, A., Goel, A., Dhayalan, J., Kamali Zare, V., Hanson, L. and Yalamanchi, S. (2023) 'The effect of hormone replacement therapy on cognition and mood', Clinical Endocrinology, 98(3), pp. 285-295. Available at: https://onlinelibrary.wiley.com/doi/10.1111/cen.14856