Gonadotropins Across the Lifespan: Their role in the Neurodevelopment-Neurodegeneration Continuum.

Gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), mediate critical reproductive functions via the hypothalamus-pituitary-gonadal axis. Their levels fluctuate across the lifespan, particularly during puberty and menopause, and across the menstrual cycle. In addition to peripheral expression, gonadotropin receptors are widely expressed in the brain, notably in memory-associated regions such as the hippocampus and cortex. Alterations in FSH and LH during reproductive transitions correlate with structural and functional brain changes. Puberty disorders, including central precocious puberty (CPP) and congenital hypogonadotropic hypogonadism (CHH), show altered gray and white matter and functional connectivity in the default mode network (DMN), which supports memory and is disrupted early in Alzheimer's disease (AD). Although preclinical evidence implicates gonadotropins in amyloid and tau pathology, studies of attention and memory have yielded inconsistent results. However, reproductive disorders such as primary ovarian insufficiency (POI) and polycystic ovary syndrome (PCOS) are associated with deficits in cognitive performance, altered DMN dynamics, and increased AD risk. Menopause, characterized by marked gonadotropin elevation, is also accompanied by alterations in brain structure, connectivity, amyloid and tau deposition, and cognition, with associations with FSH and LH that are underexplored. This review synthesizes a broad range of basic and clinical evidence across reproductive transitions and disorders, highlighting shared and distinct mechanisms by which gonadotropins influence brain development, aging, and AD risk, and suggesting directions for future research.