[Preliminary results on the residence distribution at birth of patients with Alzheimer's disease in the Saguenay-Lac-Saint-Jean/Quebec (the IMAGE project)].

The IMAGE Project is pursuing the establishment of a population-based registry of Alzheimer's disease (AD) cases in the Saguenay-Lac-Saint-Jean (SLSJ) (Quebec). The authors report on the spatial distribution at birth of 221 possible, probable and definite cases. A large network of key-informants for screening AD cases has been established over SLSJ. The spatial distribution of cases at birth and at the onset of disease has been computed by calculating the Alzheimer birth rate (ABR) on the basis of three scales: six specific geographical spheres of screening, all municipalities, and the public health departments. The statistical significance of results was determined using the theoretical Poisson and the Chi square distributions. ABR for each of the geographical spheres of screening showed no statistically significant differences considering either residence at the onset of the disease or residence at birth. Furthermore, differences were observed between rural and urban areas with an interesting trend for a higher number of cases than expected in one area of SLSJ. The spatial distribution of cases considered on the basis of residence at birth appears to show a different pattern, but no significant, from that measured on the basis of residence at the onset of disease. Screening of cases is actively being pursued all across SLSJ by the IMAGE network. There is a clear trend towards rural residence at birth of cases. It remains to see whether or not this observation is due to a geographical concentration of familial cases.