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Evidence summary

Vasomotor Symptoms: KNDy Neurons and the Thermoneutral Zone

Meridian · Women's Health After 50Generated: 4 August 2026

02Vasomotor Symptoms: KNDy Neurons and the Thermoneutral Zone

Hot flushes are a hypothalamic thermoregulatory event — and that mechanism is now a drug target.

Key takeaways

  • —Median total VMS duration in SWAN was 7.4 years; women whose symptoms begin in the early transition average over 11 years.
  • —Estradiol withdrawal — not the absolute level — narrows the thermoneutral zone; this is why abrupt MHT cessation triggers rebound flushing.
  • —KNDy neurons hypertrophy when oestrogen negative feedback is lost; NK3 antagonists (fezolinetant, elinzanetant) act on this circuit directly.
  • —Persistent VMS correlates with worse endothelial function, greater carotid intima-media thickness and higher subclinical CVD burden — it may be a marker, not just a nuisance.

Graded claims

A

Median total VMS duration exceeds 7 years

Established — RCT / guideline-gradeSWAN, Avis et al. JAMA Intern Med 2015 — 7.4 years median, 4.5 years post-FMP.

A

NK3 receptor antagonism reduces moderate-severe VMS frequency vs placebo

Established — RCT / guideline-gradeSKYLIGHT and OASIS phase 3 programmes.

B

Frequent VMS is associated with subclinical cardiovascular disease markers

Supported in defined populationsSWAN Heart, MsHeart cohorts — consistent association; causality unproven.

E

Serum estradiol level predicts individual VMS severity

Popular, weak or conflicting supportWeak and inconsistent correlation.

E

Black cohosh reliably reduces moderate-to-severe VMS

Popular, weak or conflicting supportMeta-analyses are heterogeneous and largely null against placebo; hepatotoxicity case reports exist.

Supporting references

  1. Duration of menopausal vasomotor symptoms over the menopause transition (SWAN) — Avis et al., JAMA Intern Med 2015 https://pubmed.ncbi.nlm.nih.gov/25686030/
  2. Fezolinetant for moderate-to-severe vasomotor symptoms (SKYLIGHT 2) — Johnson et al., J Clin Endocrinol Metab 2023 https://pubmed.ncbi.nlm.nih.gov/36734148/
  3. Elinzanetant for vasomotor symptoms (OASIS 1 and 2) — Pinkerton et al., JAMA 2024 https://pubmed.ncbi.nlm.nih.gov/39172446/
Educational summary for registered health professionals. Grades reflect strength of evidence at the time of writing and do not replace current national guidance, product licences or clinical judgement.