Optimising the roles played by both generalists and specialists in the diagnosis and treatment of Alzheimer's disease (AD) could have a major impact on the quality and cost of patient care. Therefore, one aim of the IMPACT survey was to characterise the similarities and differences between these 2 categories of physicians, in 5 different European countries, across a number of domains relevant to the medical care of people at risk for AD and those with the disease. Physician respondents comprised 250 generalists and 250 specialists from 5 European countries--France, Germany, Italy, Spain, and the United Kingdom. A substantial majority of generalists were either general practitioners or family physicians; the majority of specialists were neurologists. In April and May 2009, physician respondents completed a 30-minute, Web-based questionnaire during which they were presented with a number of multiple-choice-type questions concerning their knowledge of AD, approach to diagnosis and treatment of AD and experience of providing care for people with dementia. Generalists reported that 45% of their AD patients had mild symptoms at the initial visit compared with 60% for specialists (P < 0.001). Specialists claimed that they diagnose patients with AD themselves in 65% of cases versus 33% for generalists (P < 0.001). The main prescription treatment options employed were AD-specific medication (90%) and medication for mood or behaviour (78%). A similar percentage of generalists and specialists (77% and 75%) initiate drug treatment within 1 month of diagnosis. Overall, there were more similarities than differences between specialists and generalists regarding a broad spectrum of issues relating to AD; differences between countries appear to be greater than differences between physician groups.