OBJECTIVE: While nearly half of all people with Alzheimer’s disease(AD) have agitation symptoms every month, little is known about thecosts of agitation in AD. We calculated the monetary costs associatedwith agitation in older adults with AD in the UK from a NationalHealth Service and personal social services perspective. DESIGN:Prospective cohort study. SETTING: London and the South East Regionof the UK (LASER-AD study). PARTICIPANTS: 224 people with AD recruitedbetween July 2002 and January 2003 and followed up for 54 months.PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome was healthand social care costs, including accommodation costs and costs ofcontacts with health and social care services. Agitation was assessedusing the Neuropsychiatric Inventory (NPI) agitation score. RESULTS:After adjustment, health and social care costs varied significantlyby agitation, from £29 000 over a 1 year period with no agitationsymptoms (NPI agitation score=0) to £57 000 at the most severe levelsof agitation (NPI agitation score=12; p=0.01). The mean excess costassociated with agitation per person with AD was £4091 a year, accountingfor 12% of the health and social care costs of AD in our data, andequating to £2 billion a year across all people with AD in the UK.CONCLUSIONS: Agitation in people with AD represents a substantialmonetary burden over and above the costs associated with cognitiveimpairment.