This article is Part 1 of the BeMediq Scientific Spotlight series “Why the Brain Dominates Perimenopause.”It provides an evidence-informed overview of how early hormonal changes originate in central neuroendocrine regulation rather than solely in the ovaries. The publication synthesizes current findings from neuroscience, endocrinology, and chronobiology to explain how the hypothalamus, pituitary gland, circadian timing, and stress-response pathways shape early symptom development.This document is shared as an educational, non–peer-reviewed preprint version of the original article published on BeMediq.com and is intended to support broader understanding of neuroendocrine mechanisms in women’s health.