The Role of Age at Onset on the Clinical Course and Biochemical Parameters of Anorexia Nervosa

Anorexia nervosa (AN) has the highest mortality rate among psychiatric disorders, mak-ing early diagnosis and appropriate management essential. This study aims to investigate the impact of age at onset (AAO) - childhood/adolescence vs adulthood - on the course of the disorder and associated biochemical parameters. A total of 76 female patients were in-cluded and divided into two groups based on AAO (< 18 years versus ≥ 18 years). Com-parisons between groups were made using t-tests for continuous variables and χ² tests for categorical variables. Correlation analyses were performed to evaluate the relation be-tween AAO and continuous variables. Significant variables at univariate analyses were then entered into two regression models with AAO as dependent variable: a binary lo-gistic regression model with significant continuous variables at t tests as predictors, and a linear regression model with significant correlations as independent variables. The ear-ly-onset group showed significantly higher potassium levels and a lower sodi-um/potassium ratio (Na+/K+) compared to the late-onset group (potassium: t=0.93, p< 0.01; Na+/K+: t=3.39, p< 0.01). Pearson correlations revealed a strong inverse relationship be-tween AAO and potassium levels (r = -0.75, p < 0.01). Cholesterol levels (r = 0.574, p < 0.01) and Na+/K+ (r = 0.78, p = 0.01) were positively correlated with AAO. Binary logistic re-gression correctly classified 87% of cases, with a lower Na+/K+ associated with earlier on-set (OR = 2.23, p = 0.03). Linear regression confirmed that cholesterol levels (B = 0.07, p = 0.02) and Na+/K+ (B = 1.68, p < 0.01) were significantly associated with AAO. This study highlights a strong association between AAO of AN and some clinical/biochemical pa-rameters. Early-onset patients show more severe electrolyte imbalances. Late-onset cases tend to have higher cholesterol levels, suggesting increased cardiovascular risk. These findings underscore the need for personalized treatment approaches according to AAO of AN. Further studies are needed to confirm the findings reported in the present article,