Estrogen. We’ve heard it called the “angel of life, and the angel of death.” Too much can be hazardous. Too little can be problematic also. Not many people realise this, but estrogen plays a role in more bodily functions than just reproduction — in fact, estrogen has many important functions in the brain.
Studies show that decreasing levels of estrogen can cause two of the most common perimenopause symptoms — hot flashes and mood fluctuations. Read on to learn the details of this biochemistry.
Summary: What This Article Covers
The main focus of this article is the time in a woman’s life right before menopause, conveniently called perimenopause. Perimenopause can start as early as 10 years before periods stop for good (more commonly 2–4 years). The symptoms many women experience during perimenopause include hot flashes, mood instability, changes in memory and menstrual cycle irregularity — all brought on by decreasing levels of estrogen and progesterone.
Previously thought to be only involved in reproduction, estrogen has many important functions in the brain — ensuring there is enough energy for optimal brain function, promoting brain cell survival and protecting it from damage. This article highlights the changes that take place in the brain with decreasing estrogen during perimenopause, and how these brain changes present themselves in the form of mood fluctuations and hot flashes. And the short answer to the question in the title is — yes. It pretty much is.
Perimenopausal Stages and Symptoms
Menopause concludes the reproductive chapter in the feminine life cycle. Defined retrospectively as the cessation of spontaneous menses, menopause is characterised by diminished ovarian production of estrogen and progesterone and termination of production of oocytes, resulting in reproductive senescence.
Perimenopause encompasses three stages: the early menopausal transition, marked by persistent cycle irregularity; the late menopausal transition, with intervals of amenorrhoea of ≥60 days; and early postmenopause — the first year following the final menstrual period. With an average duration of about 4 years, the onset of distressing symptoms may happen as early as 10 years before termination of menstruation.
Some experts regard perimenopause as a time of great vulnerability during which an increased risk of neurological decline can emerge for a substantial proportion of women.
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The Neurological Nature of the Perimenopausal Transition
Although the classical definition of perimenopause focuses mainly on the reproductive system, perimenopause is fundamentally neurological in nature. The breadth of neurological symptoms — mood changes, insomnia, decreasing cognitive function and temperature dysregulation — suggest a disruption of centrally-regulated mechanisms. The ovarian hormones estrogen and progesterone, which are essential reproductive and neural substrates, are at the heart of this transition.
Estradiol: The Master Regulator
Operating synergistically with many biological systems, estradiol coordinates signalling and transcriptional pathways that govern energy metabolism in the brain. Specific neuroprotective actions of estradiol include its role as a potent antioxidant, its involvement in the regulation of glucose transport and aerobic glycolysis, modulation of mitochondrial function and generation of ATP, and promotion of cell survival.
A Network of Estrogen Receptors
Changes in the organisation of the estrogen receptor network within the brain or alterations of circulating estradiol levels can elicit profound consequences on neural circuit function.
The ovarian-neural estrogen axis modulates a myriad of neurological processes via a network of estrogen receptors. The locations of estrogen receptors in the brain coincide with the relevant neuroanatomical regions that regulate executive and affective functions, and vasomotor stability. Estradiol signalling via the estrogen receptors ensures that the brain effectively responds to stimuli in a timely fashion, and that neurons generate sufficient energy to meet demand.
When the estrogen receptor network undergoes uncoupling from the bioenergetics system, a hypometabolic state associated with neurological dysfunction arises — giving rise to vasomotor and mood symptoms in perimenopause.
Perimenopausal Symptoms and Compromised Brain Bioenergetics
Hot Flashes and Glucose Metabolism
Experienced by approximately 80% of women during perimenopause, hot flashes commonly co-occur with sleep disturbances, mood changes, pain and decline in cognitive function. Increasing evidence suggests a tight-knit relationship between hot flashes and impaired glucose homeostasis — glucose levels and the degree of insulin resistance correlate with frequency of hot flashes.
Fluctuating levels of estradiol coincide with a decline in brain bioenergetics and a shift towards a metabolically compromised phenotype — an effect that can be rescued with hormone replacement therapy (HRT). In symptomatic female patients receiving HRT during perimenopause, glucose metabolism is preserved in brain regions with estrogen-dependent neurological functions.
The Neuroendocrine Nature of Hot Flashes
As women approach menopause, fluctuations in ovarian function have a profound impact not only on the hormonal milieu, but on neurotransmitter levels and signalling as well. Estradiol directly modulates neurotransmitter systems — activating receptors, upregulating neurotransmitter biosynthesis and release, and blocking re-uptake and degradation.
Neurotransmitters (norepinephrine and serotonin) directly regulate the thermoneutral zone — the homeostatic range of body temperature. As estradiol declines, brain norepinephrine levels increase, inducing a narrowing of the thermoneutral zone. Additionally, decreased estradiol results in upregulation of monoamine oxidase-A (MAO-A) — the enzyme responsible for degradation of serotonin — increasing serotonin turnover. Therefore, reduced serotonin function during perimenopause and an abundance of norepinephrine signalling appear to have vasomotor manifestations in the context of a declining hormonal environment.
For women whose hot flashes, mood changes and sleep disturbances may involve both hormonal and neurotransmitter imbalances, our Neurotransmitter & Saliva Hormone Test I measures GABA, serotonin, dopamine, norepinephrine and epinephrine alongside saliva hormones — providing a comprehensive neurochemical and hormonal picture to guide targeted support.
“The Change”: What Comes Next
Perimenopause is a developmental change in the evolving landscape of endocrine and neurological transformations. The new neuroendocrine environment of perimenopause characterised by continuous change may render some women vulnerable to neurodegenerative disorders late in life. Multiple conditions emerging during perimenopause — insomnia, depression, memory impairment and cognitive decline — may be associated with an increased risk for dementia, including Alzheimer’s disease.
Hormone replacement therapy serves as the logical choice, given the tremendous impact that estradiol elicits on the brain. Timing of the administration of HRT appears to be critical to the effectiveness of the therapeutic approach, with perimenopause providing the optimal window of opportunity for introducing exogenous hormones. Personalising HRT may be the best strategy for each individual patient to sustain neurological bioenergetic capacity.
For women who want a comprehensive hormonal and wellness assessment with specialist interpretation to guide HRT decisions, our Advanced Female Wellness Test (with Specialist Doctor Report) provides a broad picture of hormonal health with a full specialist doctor report to guide next steps.
Originally by Dr. Kate Placzek, ZRT Laboratory. Reproduced with permission. Last reviewed: May 2026.