Over 2000 randomized trials are reported in the literature for the treatment of dementia and cognitive decline. Yet the responses to the question, ‘Which treatments are effective in dementia?’ are likely to be various and conflicting. Wide variation in practice exists, and for drug therapy, where information is more readily available, different treatments are used in different countries. For example, only one drug (Hydergine) is licensed in the UK for dementia, though rarely used, while there are over 30 drugs in use in Japan for dementia and cognitive decline,five in Spain, and two in the USA. This inconsistency is likely to be even greater for interventions of psychological and behavioural therapies, environmental therapy and the organization of care.