Influence of dehydroepiandrosterone sulphate levels on the slower age-related decline in grey matter in younger women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is characterized by excess androgens, ovulatory disorders and a higher prevalence of obesity and metabolic disturbances including Type 2 diabetes, hyperlipidaemia and hypertension, some of which are risk factors for neurodegenerative disorders such as Alzheimer's disease and brain atrophy. However, it is unclear whether brain ageing occurs more rapidly in women with PCOS compared with those without PCOS. Except for the hypothalamic-pituitary-gonadal axis involved in the conventional ovulatory process, little is known regarding the role of the grey matter in the pathogenesis of PCOS, and limited existing studies examining brain structures in PCOS have shown inconsistent results. This case-control study aimed to investigate the age-related differences in total and regional brain grey matter volume and average cortical thickness in young women with and without PCOS by using brain magnetic resonance imaging to understand whether women with PCOS exhibit distinctive patterns of brain ageing, and their association with factors including obesity, hyperandrogenism and metabolic disturbances. Seventy-six women diagnosed with PCOS and 68 age-matched women without PCOS (aged 20-35 years) underwent brain magnetic resonance imaging to measure grey matter volume and cortical thickness. Anthropometric, hormonal and metabolic measurements were conducted to assess their associations with the investigated brain structures. In women without PCOS, increasing age was significantly correlated with a decrease in global grey matter volume (<i>r</i> = -0.5598, <i>P</i> < 0.0001), while this association was not significant in women with PCOS (<i>r</i> = -0.1475, <i>P</i> = 0.204). The decline in grey matter volume with age differed significantly between the two groups regardless of obesity (body mass index exceeding 25 kg/m²), especially in the frontal, parietal, occipital and temporal regions. After adjusting for dehydroepiandrosterone sulphate (DHEAS) levels, the negative association between age and global grey matter volume became statistically significant in women with PCOS. Increasing age was also significantly associated with a decrease in global cortical thickness in women without PCOS, but not in women with PCOS. Such negative association between global cortical thickness and age was particularly stronger in women with obesity compared with those without. The negative association between age and global cortical thickness in women with PCOS became pronounced after adjusting for DHEAS levels. Women with PCOS experience a milder grey matter loss with age compared with women without PCOS. The neuroprotective effect of high DHEAS levels in women with PCOS may be implicated in this relationship.