The invention provides methods for the prophylaxis or treatment of one or more disorders associated with dementia comprising administering to a patient in need thereof, a therapeutically effective amount of (i) a 5-HT2A or 5-HT2A/D2 receptor ligand and (ii) a PDE1 inhibitor, and pharmaceutical compositions comprising (i) a 5-HT2A or 5-HT2A/D2 receptor ligand and (ii) a PDE1 inhibitor.