Gender differences in incidence of mild neurocognitive disorder and predictor factors: Initial insights from the Birjand longitudinal aging study (BLAS) 

Background Mild neurocognitive disorder (MNCD) is a common condition in older adults that often precedes dementia. Identifying its risk factors is essential for developing effective, targeted prevention strategies. This study aimed to determine the incidence of MNCD and its gender-specific risk factors in a population of older adults in Iran. Methods This research was part of the Birjand Longitudinal Aging Study (BLAS). We followed a cohort of 1,029 adults (mean age 68.4 years; 47.8% female) from 2018 to 2023. MNCD was diagnosed according to established DSM-V criteria and confirmed by a neurologist. Statistical analyses were performed to calculate incidence rates and identify significant risk factors. Results The overall incidence rate of MNCD was 54.40 per 1,000 person-years. The incidence was significantly higher in women (75.08) than in men (41.92). Significant risk factors for the entire group were older age, low education (≤ 5 years), and having three or more children. Daytime napping had a protective effect. Crucially, analysis revealed distinct gender-specific risks: for women, poor health-related quality of life was a major risk factor, while for men, the primary risks were benzodiazepine use and a history of stroke. Conclusion There is a high incidence of MNCD among older adults in Iran, with a significant disparity between women and men. The risk profiles are distinctly different for each gender, underscoring the necessity for sex-tailored prevention and intervention programs that address these unique risk factors.