Prevalence of Dementia and Cognitive Complaints in the Context of High Cognitive Reserve: A Population-Based Study

<div><p>Objectives</p><p>This study aimed to assess the prevalence of dementia and cognitive complaints in a cross-sectional sample of Luxembourg seniors, and to discuss the results in the societal context of high cognitive reserve resulting from multilingualism.</p><p>Methods</p><p>A population sample of 1,377 people representative of Luxembourg residents aged over 64 years was initially identified via the national social insurance register. There were three different levels of contribution: full participation in the study, partial participation, and non-participation. We examined the profiles of these three different samples so that we could infer the prevalence estimates in the Luxembourgish senior population as a whole using the prevalence estimates obtained in this study.</p><p>Results</p><p>After careful attention to the potential bias and of the possibility of underestimation, we considered the obtained prevalence estimates of 3.8% for dementia (with corresponding 95% confidence limits (CL) of 2.8% and 4.8%) and 26.1% for cognitive complaints (CL = [17.8–34.3]) as trustworthy.</p><p>Conclusion</p><p>Based on these findings, we postulate that high cognitive reserve may result in surprisingly low prevalence estimates of cognitive complaints and dementia in adults over the age of 64 years, which thereby corroborates the longer disability-free life expectancy observed in the Luxembourg population. To the best of our knowledge, this study is the first to report such Luxembourgish public health data.</p></div

Characteristics for both full and partial participants.

<p>* to people of a similar age</p><p>^a<i>p</i>-values derived from Chi-squared tests;</p><p>^b<i>p</i>-values derived from Fisher's exact tests.</p><p>^# used with a cut-off based on the algorithm: Total score ≥ 3 or score for question 5 = 1 or score of the sum of questions A, 4, 5, 7, 8 ≥ 2.</p><p>Characteristics for both full and partial participants.</p

Luxembourg: The conjunction of a longer disability-free life expectancy at 65 years, a high cognitive reserve, and a low estimates of dementia?

<p>Luxembourg: The conjunction of a longer disability-free life expectancy at 65 years, a high cognitive reserve, and a low estimates of dementia?</p

Distribution of data available for the three types of population.

<p>^a: the <i>p</i>-value was derived from Chi-squared test</p><p>^b: the <i>p</i>-value was derived from Kruskal-Wallis test</p><p>Distribution of data available for the three types of population.</p

Population pyramid of the overall participants (A) and of seniors from Luxembourg (B): Comparison by gender and age (C).

<p>(A) Overall participants: per age group and gender, numbers compared to the total amount of subjects over 64 years old. (B) Luxembourgish seniors: per age group and gender, numbers compared to the total amount of subjects over 64 years old. (C) Representativeness depending on age groups and gender: the overall participants compared with the Luxembourgish seniors. Overall participants include full-participants and partial participants to the MemoVie study (<i>n</i> = 438). National statistics 2006, from: <a href="http://www.statistiques.public.lu/stat/TableViewer/tableView.aspx?ReportId=385&IF_Language=eng&MainTheme=2&FldrName=1" target="_blank">http://www.statistiques.public.lu/stat/TableViewer/tableView.aspx?ReportId=385&IF_Language=eng&MainTheme=2&FldrName=1</a> (<i>n</i> = 66,000)</p

Answers supplied for “lifestyle.”

<p>(A) Lifestyle distribution depending on population. (B) Representativeness depending on lifestyle: the overall participants compared to the Luxembourgish seniors. From the full-participants (<i>n</i> = 286), the overall participants (<i>n</i> = 421) and from the general population ≥ 65 years of Luxembourg (source: Statec 2001, <i>n</i> = 57,230). For this criteria, the overall participants (<i>p</i> < 0.0001) as well as the group of full-participants (<i>p</i> < 0.0001), were significantly different from the Luxembourgish seniors (Chi-squared test).</p

Set of data according to the groups of population.

<p>Set of data according to the groups of population.</p

Prevalence estimates of dementia and cognitive complaints.

<p>^#: calculation obtained using sampling scheme and target population size</p><p>Prevalence estimates of dementia and cognitive complaints.</p

Odds ratio for occurrence of CIND for practicing cognitively stimulating activities and multilingualism during lifespan.

<p>Multilingualism was studied through its two classifications: ¹subjects using 2 languages versus more than two; ²subjects using only 3, only 4 or more than four languages; CSC: cognitively stimulating component.</p

Acquisition of multilingualism in the studied population.

<p><u>Part A. Typical progression: sequential and increasing process of learning and practicing multilingualism.</u> (For each stage of multilingualism, either individuals stayed at a specified level, or they progressed to the next step i.e. they learned an additional language.) Description of the 6 models of progression found among the 168 individuals for which the learning process represents the acquisition of one language after another (keeping the practice of all of them). <u>Part B. Atypical and unordered progression of learning and practicing multilingualism</u>. Illustration of the 6 models of atypical progression exhibited by the 64 subjects learning 2 or 3 languages in the same period of time and/or losing the practice of one or 2 languages at some point in their lives.</p