Drug prescribing is an essential component in the management of pathologies and functional capacity of older patients. However, some medicines may be dangerous for patients. The potentially inappropriate drug prescribing (PIDP) among older patients represents a significant cause of morbidity. The aim of this study was to compare the clinical characteristics and the healthcare costs of elderly patients according to potentially inappropriate drug prescribing. Analyses were conducted using data from the MAPT (Multidomain Alzheimer Preventive Trial) study. An algorithm was constructed to detect potentially inappropriate drug prescribing and was based on different explicit criteria: the European List of potentially inappropriate medications, the STOPP and START tools version 2, Alert and Mastering of Iatrogenesis indicators (AMI) of the French High Authority for Health (HAS), the market withdrawals and the Summary of Product Characteristics (SPC) for contraindications. We performed the cost analysis from the French national health insurance perspective. The costs are reported as means and bootstrap 95% confidence intervals. At baseline, the algorithm analysed prescriptions from included patients (N=1525 aged 75.3±4.4 years; 64% women (N=978)). Among the included patients, 80.4% had PIDP (N=1226). The patients with PIDP (versus without PIDP) didn’t differ regarding sex, education levels, Fried frailty phenotype, intrinsic capacity domains (cognitive, psychological, locomotion and vitality). The patients with PIDP were slightly older (75.3 vs 74.8, p=0.028), had more prescribed drugs (5.4 vs 2.0, p<0.001), and more comorbidities (p= 0.029) (Charlson index) than those without PIDP. The average healthcare costs per patient over 6 months were 723€ [636€; 831€] for patients with PIDP and 658€ [540€; 788€] for patients without PIDP. Participants did not differ, as a function of PIDP, in terms of functional capacity and frailty, but differed regarding co-morbidities. These results have to be confirmed by a multivariate analysis on longitudinal data.