SOCIOECONOMIC BURDEN OF ALZHEIMER’S DISEASE IN ITALY AND DELIRIUM CASELOAD IN AN ACUTE GERIATRIC SETTING: A TWO-STUDY OBSERVATIONAL THESIS.

Background. Dementia is an acquired syndrome characterised by progressive cognitive decline and loss of independence. Delirium is an acute neuropsychiatric disorder that often occurs during hospitalisation, frequently in the context of dementia. Both conditions carry substantial clinical and socioeconomic burdens. Given rapid population ageing, judicious resources allocation is critical; however, national evidence on the socioeconomic impact of dementia remains limited, and dedicated care pathways for older adults with dementia or delirium are under-implemented. Aims. To generate policy-relevant evidence to inform sustainable, equitable, and outcomes-oriented care models for Italy’s ageing population. This thesis integrates two studies to: (1) estimate the socioeconomic burden of Alzheimer’s disease (AD) among community-dwelling patients, from both the National Health Service and societal perspectives; and (2) quantify delirium prevalence/incidence in an Acute Geriatric Unit (AGU), model daily delirium-probability trajectories and evaluate their prognostic value for 3-month mortality. Methods. Study 1 was a cross-sectional study conducted in seven Italian memory clinics, enrolling patients aged ≥50 years with AD across severity stages and their caregivers. A cost-of-illness approach captured health- and social-care resource use over the prior three months (medications, home/community services, caregiver work impact). Multivariable regression identified determinants of total costs. Study 2 was a prospective cohort study enrolling older adults consecutively admitted to the AGU of the IRCCS Foundation San Gerardo dei Tintori (Monza). Sociodemographic and comprehensive clinical data were collected. In-hospital delirium-probability trajectories were derived using group-based trajectory modelling; associations with 3-month mortality were estimated with Poisson regression adjusted for age, sex, frailty and serum albumin. Results. Study 1: 262 patient-caregiver dyads were enrolled [median patient age 75 years (Q1–Q3: 70–81); 46.9% men; 18.7% Mild Cognitive Impairment, 30.9% mild AD, 30.5% moderate AD, 19.9% severe AD]. Mean monthly per-patient costs rose with severity: from €195 to €304 in the NHS perspective, and from €426 to €1,644 in the societal perspective. Expenditure fell predominantly on families and society via formal paid care, out-of-pocket spending, and especially caregiver productivity losses. Greater neuropsychiatric symptom burden independently increased total costs, whereas better patient instrumental functioning reduced them. Patient health-related quality of life declined with disease severity, with a milder parallel decline among caregivers. Study 2: 639 patients were enrolled [median age 87 years (Q1–Q3: 84–90); 53.2% women]. Delirium prevalence at admission was 38% (95% CI: 34–42%), and in-hospital incidence 14% (95% CI: 11–18%). Among the 301 patients with delirium, three probability trajectories emerged: High (40.2%), Medium (31.9%), and Medium-to-Low (27.9%). Compared with the Medium-to-Low class, adjusted 3-month mortality risk was higher in the Medium (RR 1.56, 95%CI 1.02–2.36) and High (RR 2.07, 1.41–3.05) trajectories. Conclusions. AD-related costs escalate with severity and are largely borne by families in the community. In hospital, delirium is common, and certain trajectories are strongly associated with short-term mortality. Together, there findings link the economic and clinical-epidemiological dimensions of older adults’ care across the home–hospital continuum, providing practical foundations for targeted, evidence-based investments that may reduce costs while improving outcomes for patients and caregiver in dementia and delirium fields.