Prevalence of Alzheimer's type dementia in an elderly Arab population

The aim of this study was to estimate the prevalence of dementia of the Alzheimer type (DAT) in an Arab Israeli community. Epidemiological studies of dementia have rarely been reported in Arab populations. The target population, aged 60 years or older, comprised 821 persons (362 males) who, on 1 October 1995, were residents of the rural area of Wadi Ara. These persons were examined for symptoms of dementia (DSM-IV criteria), using a semistructured questionnaire for collection of demographic and medical data. Age, gender, and education-specific prevalence rates were calculated for this population and compared to those obtained in other studies. DAT was diagnosed in 20.5% of this population. Its prevalence increased steeply with age, from 8% among those younger than 70 years to 33% among those aged 70-79 and 51% among those 80 years or older. Illiteracy was very common in this population, and strongly associated with higher prevalence of DAT (27% vs. 4%, P < 0.001). DAT was more prevalent among females than males (25% vs. 15%, P < 0.001). However, illiteracy was also significantly more frequent among women (96% vs. 42%, P < 0.001). After correction for illiteracy, the gender difference lost statistical significance. Few women smoked, but among men, the prevalence of DAT in those who smoked was lower as compared to non-smokers (14% vs. 23%, a non-significant difference). These results were confirmed by logistic regression wherein DAT was included as the dependent variable and age, illiteracy, gender and smoking as independent variables (OR = 2.8, 2.8, 1.2 and 0.7, respectively; P < 0.005 for each, except for smoking). Our findings suggest that this population is unique because of extremely high rates of dementia. While the results support a protective effect of schooling against the development of dementia, other factors (e.g. genetic) must be sought to explain this high frequency.