The Rotterdam Study investigated the prevalence of dementia and its subtypes in a general population, focusing on the relationship between education and dementia. The study involved 7528 participants aged 55-106 years in Ommoord, a suburb of Rotterdam. A total of 474 cases of dementia were detected, giving an overall prevalence of 6.3%. Alzheimer's disease was the main subtype, accounting for 72% of cases, and was the primary cause of the age-related increase in dementia prevalence. The prevalence of dementia was significantly higher in individuals with lower levels of education, and this association was not due to confounding by cardiovascular disease. The study found an inverse dose-response relationship between education and dementia, particularly for Alzheimer's disease. The prevalence of dementia increased exponentially with age, with about one-third of people aged 85 and over having dementia. Three-quarters of all dementia cases were due to Alzheimer's disease. The study also showed that the prevalence of dementia was higher in women than in men in the 80-89 age group. The study used a three-phase diagnostic approach to assess dementia, including a brief cognitive test, a detailed examination by a physician, and a third extensive examination by a neurologist and neuropsychologist. The results showed that the relative risk of dementia decreased with increasing educational status. The study also found that the association between education and dementia was not explained by cardiovascular disease. The study is the largest European study of its kind, providing more precise estimates of dementia prevalence. It showed slightly lower prevalences below the age of 75 and slightly higher prevalences above the age of 80 compared to a pooled reanalysis of 12 European studies. The study concluded that the prevalence of Alzheimer's disease increases with age and that dementia, particularly Alzheimer's disease, is inversely related to educational status. The study also found that the prevalence of dementia was higher in groups with less education, and this effect could not be explained by cardiovascular disease.The Rotterdam Study investigated the prevalence of dementia and its subtypes in a general population, focusing on the relationship between education and dementia. The study involved 7528 participants aged 55-106 years in Ommoord, a suburb of Rotterdam. A total of 474 cases of dementia were detected, giving an overall prevalence of 6.3%. Alzheimer's disease was the main subtype, accounting for 72% of cases, and was the primary cause of the age-related increase in dementia prevalence. The prevalence of dementia was significantly higher in individuals with lower levels of education, and this association was not due to confounding by cardiovascular disease. The study found an inverse dose-response relationship between education and dementia, particularly for Alzheimer's disease. The prevalence of dementia increased exponentially with age, with about one-third of people aged 85 and over having dementia. Three-quarters of all dementia cases were due to Alzheimer's disease. The study also showed that the prevalence of dementia was higher in women than in men in the 80-89 age group. The study used a three-phase diagnostic approach to assess dementia, including a brief cognitive test, a detailed examination by a physician, and a third extensive examination by a neurologist and neuropsychologist. The results showed that the relative risk of dementia decreased with increasing educational status. The study also found that the association between education and dementia was not explained by cardiovascular disease. The study is the largest European study of its kind, providing more precise estimates of dementia prevalence. It showed slightly lower prevalences below the age of 75 and slightly higher prevalences above the age of 80 compared to a pooled reanalysis of 12 European studies. The study concluded that the prevalence of Alzheimer's disease increases with age and that dementia, particularly Alzheimer's disease, is inversely related to educational status. The study also found that the prevalence of dementia was higher in groups with less education, and this effect could not be explained by cardiovascular disease.