A study by researchers from the Epidemiology Research Unit (EPIUnit) of the Instituto de Saúde Pública da Universidade do Porto (ISPUP), which evaluated the prevalence of cognitive impairment and dementia in a sample of the Portuguese population, found that the main cause of dementia in Portugal is related to vascular factors (vascular dementia) and not to Alzheimer’s disease, contrary to what happens in most Western European countries. The positive message is that vascular dementia can be prevented by modifying lifestyles.
Given the growing aging of the population, cognitive impairment and dementia are increasingly prevalent worldwide, affecting the quality of life of millions of patients and their families. Understanding the main causes and how to prevent cognitive decline is therefore important in order to achieve gains in health.
In Portugal, the only epidemiological study to evaluate cognitive decline and dementia in the Portuguese population dates back to 2003 and points to a prevalence of 2.7% of the disease in individuals aged 55 to 79 years.
The present study, which goes into more detail than the previous one, evaluated the prevalence of cognitive impairment and dementia in a sample of 730 individuals in the EPIPorto cohort (a population-based study that has evaluated, for 18 years, the health determinants of the adult population living in Porto) and tried to identify their most frequent causes.
The results show that about 4.5% of individuals older than 55 years have dementia or mild cognitive impairment.
The research also found that the most prevalent type of dementia in Portugal is vascular dementia and not Alzheimer’s, thus counteracting the trend in most western countries.
The main explanation for these differences is the high incidence of stroke in Portugal compared to other countries, which may explain the prevalence of vascular dementia in our country. In fact, because of the damage it causes to the brain, stroke is a risk factor for the development of this type of dementia.
Additionally, the reason for this difference may lie in the fact that “Portugal is the country with the highest consumption of fish, particularly fatty fish, which seems to be associated with a lower risk of dementia and Alzheimer’s disease”, says Luís Ruano, the first author of the study. Another explanation may be the “lower prevalence of the ε4 allele of the APOE gene among the Portuguese population, which is the most common genetic risk factor for Alzheimer’s disease“, he adds.
The research published in the American Journal of Alzheimer’s Disease & Other Dementias® “carries an important public health message regarding the epidemiology of dementia in Portugal and reveals a high potential for the prevention and management of vascular dementia”, says Luís Ruano.
This type of dementia can be prevented and, for example, primary prevention measures, such as “a healthy diet, regular exercise and control of major cardiovascular risk factors” should be used. Such recommendations can help ease the burden on patients, families and society.
The study is called Prevalence and Causes of Cognitive Impairment and Dementia in a Population-Based Cohort from Northern Portugal. The researchers Henrique Barros, Natália Araújo, Mariana Branco, Rui Barreto, Sandra Moreira, Ricardo Pais, Vítor Tedim Cruz and Nuno Lunet also participated in the research.
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