Cognitive impairment particularly affects the elderly and represents a major obstacle to their autonomy and quality of life. In Portugal, there are few studies identifying the prevalence of cognitive impairment among the elderly population and the incidence or number of new cases of this condition.
The Instituto de Saúde Pública da Universidade do Porto (ISPUP) sought to contribute with more knowledge in this area through a study that calculated the prevalence and incidence of cognitive impairment in a sample of 586 residents in the city of Porto, aged between 65 and 85 years, who were followed between 1999 and 2015.
It was concluded that 91 individuals (15.5%) were diagnosed with cognitive impairment at the time they were recruited to participate in the research, and that between the years 2005 and 2015, 48 people developed this condition, which corresponds to an incidence of 26.97 new cases per 1000 people each year, a value that, even so, is below the incidence of most countries in Europe. Women, older people and those with less education were the ones who were more likely to develop cognitive impairment during the analysed time period and should therefore be the most targeted by public health strategies.
As explained by Ricardo Pais, first author of the study, developed under the Epidemiology Research Unit (EPIUnit) of ISPUP and coordinated by Henrique Barros, “cognitive impairment increases the risk of dementia and mortality among the older population. It is characterised by an alteration in the person’s cognitive state, in which they begin to present memory failures, as well as difficulties in learning and concentrating when carrying out specific tasks, which would not be expected for their age and level of education”.
As life expectancy increases, the risk of disease and vulnerability among older people is expected to rise and more cognitive problems are likely to occur. Therefore, epidemiological data is needed to assess the potential of preventive interventions among this population.
It was precisely with the aim of contributing with more data about Portugal that ISPUP carried out this study, published in the journal BMC Geriatrics. In addition to the prevalence and incidence of cognitive impairment, the researchers sought to understand the role of risk factors such as age, gender, education, employment status (continued professional activity or retirement) and marital status in brain function.
A sample of 586 people was used, aged between 65 and 85 years old, residents in the city of Porto, and members of the EPIPorto cohort – a longitudinal study that has, since 1999, the evaluated the health status of a set of individuals living in the city.
The participants in the newly disclosed research were assessed at the time of their recruitment to the cohort, between 1999 and 2004. Information on their socio-demographic characteristics and cognitive function was collected, which allowed the researchers to calculate the number of existing cases (prevalence), among the participants at that moment.
In addition to this first assessment, there were also two subsequent assessments of the cohort, between 2005 and 2015, which allowed calculating how many new cases (incidence) of cognitive impairment arose over those years among participants who had not been diagnosed with the condition at the time of the first assessment.
15.5% of participants diagnosed with cognitive impairment
At the time of recruitment, 91 participants (15.5%) out of 586 were diagnosed with cognitive impairment. According to Ricardo Pais, this figure is within the estimated prevalence range for the European population: 7.7 to 33.1%.
The prevalence was higher in women than in men and higher in individuals who were aged between 80 and 85 years old, a result that is in line with other studies that associate cognitive impairment and dementia with increasing age. The highest number of cases was also detected in less educated people.
48 people developed cognitive impairment over the study period
In subsequent evaluations of the participants, which took place over ten years, 48 new cases of cognitive impairment appeared among people who had not been diagnosed with the condition when they first entered the research.
This corresponds to an incidence of 26.97 new cases per 1000 people each year. The incidence found in this sample is below that reported by most countries in Europe for this population.
According to the ISPUP researcher, “at the moment, we have no data that can explain why our incidence is lower than other European countries, and future research is needed to better ascertain the reasons”.
Cognitive impairment particularly affects the elderly and represents a major obstacle to their autonomy and quality of life. In Portugal, there are
The emergence of new cases of cognitive impairment was also higher among women, older people and individuals with less education. The researchers did not find an association between marital status, retirement age and the risk of cognitive impairment.
The study’s contribution
For Ricardo Pais, “this article contributes with relevant information regarding the prevalence and incidence of cognitive impairment in Portugal. We were able to present an estimate of the incidence of cognitive impairment in a representative sample of the Portuguese elderly population and understand what the main risk factors for the development of this condition are”.
“Women, the elderly and the less educated are the main risk groups for the development of cognitive impairment and, therefore, health policies should elect them as priority groups, in order to prevent their condition from progressing to dementia or Alzheimer’s disease,” he adds.
The research, called Prevalence and incidence of cognitive impairment in an elder Portuguese population (65-85 years old), is also signed by researchers Luís Ruano, Ofélia Carvalho and Carla Moreira.