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

Protective effect of bilingualism on aging, MCI, and dementia: A community-based study

INTRODUCTION

Lifelong bilingualism is associated with a delayed age at onset of dementia, but evidence from community-based studies is limited. We investigated the relationship between bilingualism and the prevalence of cognitive impairment in a linguistically diverse community.

METHODS

A door-to-door community study was conducted from January to December 2021 in urban Bengaluru, India. 1234 individuals aged ≥60 years participated in the study. Participants were diagnosed with no cognitive impairment (NCI), mild cognitive impairment (MCI), or dementia using established diagnostic criteria.

RESULTS

Dementia prevalence was higher in monolinguals (4.9%) than bilinguals (0.4%) (P = .001). The prevalence of MCI was also higher in monolinguals (8.5%) than bilinguals (5.3%) (P = .001). The study also revealed better cognitive function in bilinguals than monolinguals with NCI, after controlling for confounding variables.

DISCUSSION

The current study provides significant support for the protective effect of bilingualism on cognitive impairment in an urban community with extensive bilingual interactional contexts in everyday life.

HIGHLIGHTS

Bilingualism has been demonstrated to protect against dementia and mild cognitive impairment in a linguistically diverse community with extensive code-switching contexts. Bilingual older individuals had superior baseline cognitive performance compared to monolingual older individuals. Bilingualism was found to have an independent effect on general cognition after adjusting for major social determinants of health in the group without cognitive impairment.

Programme Dementia Prevention (pdp): A Nationwide Program for Personalized Prevention in Luxembourg

BACKGROUND

With continuously aging societies, an increase in the number of people with cognitive decline is to be expected. Aside from the development of causative treatments, the successful implementation of prevention strategies is of utmost importance to reduce the high societal burden caused by neurodegenerative diseases leading to dementia among which the most common cause is Alzheimer's disease.

OBJECTIVE

The aim of the Luxembourgish "programme dementia prevention (pdp)" is to prevent or at least delay dementia in an at-risk population through personalized multi-domain lifestyle interventions. The current work aims to provide a detailed overview of the methodology and presents initial results regarding the cohort characteristics and the implementation process.

METHODS

In the frame of the pdp, an extensive neuropsychological evaluation and risk factor assessment are conducted for each participant. Based on the results, individualized multi-domain lifestyle interventions are suggested.

RESULTS

A total number of 450 participants (Mean age = 69.5 years; SD = 10.8) have been screened at different recruitment sites throughout the country, among whom 425 participants (94.4%) met the selection criteria.

CONCLUSIONS

We provide evidence supporting the feasibility of implementing a nationwide dementia prevention program and achieving successful recruitment of the target population by establishing a network of different healthcare providers.

Subjective memory complaints: Prevalence, associated factors and sex differences in the ELSI-Brazil study

BACKGROUND

Subjective memory complaints (SMCs) are a possible prodrome of cognitive decline but are understudied in low- and middle-income countries (LMIC). We aimed to estimate the prevalence of SMCs in a large, nationally representative sample of older adults from Brazil and to identify sociodemographic and health-related factors that are associated with SMCs independently of objective memory.

METHODS

Baseline data (n = 7831) from the ELSI-Brazil study, a national representative sample of adults aged 50 and over. They were asked to rate their memory and then divided into two groups - having or not having SMCs. Logistic regression models were used to estimate the association of demographic characteristics, health related factors, objective memory performance and disability in basic (b-ADL), instrumental (i-ADL), and advanced (a-ADL) activities of daily living associated with SMCs. Whether sex was an effect modifier of the association between age and objective memory performance and SMCs was also tested.

RESULTS

Of the sample, 42% (95% CI; 39.9-43.9) had SMCs, and it was higher among women (46.9%) than men (35.9%). SMC prevalence decreased with age among women and increased among men, and for both it decreased with better cognitive performance. Fully adjusted logistic regression model showed that older age, higher education, higher b-ADL scores, and better cognitive performance were associated with decreased SMCs, while being female, with higher number of chronic conditions, higher i-ADL scores, worst self-rated health, and an increased number of depressive symptoms were associated with increased SMCs. However, the interaction test (p < 0.001) confirmed that increased age was associated with decreased SMCs only among women, and that better objective memory performance was associated with decreased SMCs only among men.

CONCLUSIONS

SMCs are common in the Brazilian older population and are associated with health and sociodemographic factors, with different patterns between men and women. There is a need for future studies looking at the cognitive trajectory and dementia risk in older adults with subjective cognitive complaints.

PRedicting the EVolution of SubjectIvE Cognitive Decline to Alzheimer's Disease With machine learning: the PREVIEW study protocol

BACKGROUND

As disease-modifying therapies (DMTs) for Alzheimer's disease (AD) are becoming a reality, there is an urgent need to select cost-effective tools that can accurately identify patients in the earliest stages of the disease. Subjective Cognitive Decline (SCD) is a condition in which individuals complain of cognitive decline with normal performances on neuropsychological evaluation. Many studies demonstrated a higher prevalence of Alzheimer's pathology in patients diagnosed with SCD as compared to the general population. Consequently, SCD was suggested as an early symptomatic phase of AD. We will describe the study protocol of a prospective cohort study (PREVIEW) that aim to identify features derived from easily accessible, cost-effective and non-invasive assessment to accurately detect SCD patients who will progress to AD dementia.

METHODS

We will include patients who self-referred to our memory clinic and are diagnosed with SCD. Participants will undergo: clinical, neurologic and neuropsychological examination, estimation of cognitive reserve and depression, evaluation of personality traits, APOE and BDNF genotyping, electroencephalography and event-related potential recording, lumbar puncture for measurement of Aβ42, t-tau, and p-tau concentration and Aβ42/Aβ40 ratio. Recruited patients will have follow-up neuropsychological examinations every two years. Collected data will be used to train a machine learning algorithm to define the risk of being carriers of AD and progress to dementia in patients with SCD.

DISCUSSION

This is the first study to investigate the application of machine learning to predict AD in patients with SCD. Since all the features we will consider can be derived from non-invasive and easily accessible assessments, our expected results may provide evidence for defining cost-effective and globally scalable tools to estimate the risk of AD and address the needs of patients with memory complaints. In the era of DMTs, this will have crucial implications for the early identification of patients suitable for treatment in the initial stages of AD.

TRIAL REGISTRATION NUMBER (TRN)

NCT05569083.

Old age takes its toll: Long-run projections of health-related public expenditure in Luxembourg

This paper simulates long-term trends in Luxembourg's public expenditure on healthcare and on long-term care. We combine population projections with micro-simulations of individuals' health status that account for their demographic, socio-economic characteristics and their childhood circumstances. Model equations estimated on data from the SHARE survey and from several branches of Social Security provide a rich framework to study policy-relevant applications. We simulate public expenditure on healthcare and long-term care under different scenarios to evaluate the separate contributions of population ageing, costs of producing health-related services, and the distribution of health status across age cohorts. Results suggest that rising per capita expenditure on healthcare will mostly result from production costs, while rising expenditure on long-term care will mostly reflect population ageing.

Can Speaking More Than One Language Help Prevent Alzheimer's Disease?

Alzheimer's disease (AD) is an age-related neurocognitive disorder that is epidemic in the elderly population. Currently, there are limited pharmacological interventions, and this has heightened the urgency to identify potential preventable or modifiable risk factors that promote resilience to the neuropathological effects of AD. The regular use of two or more languages is one such factor that may increases cognitive reserve through the long-standing executive control involved in managing multiple languages in the brain. There is also evidence that bilingualism is associated with increased brain reserve or maintenance, particularly in frontal-executive structures and networks. This review examines the current, sometimes conflicting literature on bi/multilingualism and AD. These studies have confounding variations in the assessment of age of second language onset, language proficiency, language usage, and whether determining incidence of AD or age of symptom onset. Despite these limitations, most publications support the presence of increased frontal-executive reserve that compensates for the development of AD neuropathology and, thereby, delays the emergence of clinical symptoms of dementia by about 4-5 years. Although regularly speaking more than one language does not protect against AD neuropathology, the delay in its clinical expression has a potentially significant impact on the lifelong morbidity from this age-related disease. Learning other languages may be an important modifiable factor for delaying the clinical expression of AD in later life.

Cognitive functioning following traumatic brain injury in older adults: associations with social participation and health-related quality of life

OBJECTIVES

To describe objective and subjective cognitive functioning older adults who sustained TBI at age 65 or over, and to determine whether cognitive functioning is associated with health-related quality of life (HRQoL) and social participation.

METHOD

The sample consisted of 40 individuals with TBI (mean age = 73 years; 65% mild, 35% moderate/severe TBI). On average 15 months post-injury, they completed measures of objective and subjective cognitive functioning (Telephone Interview for Cognitive Status-Modified, Alphaflex, Medical Outcomes Study Cognitive Functioning Scale), HRQoL (SF-12), and social participation (Participation Assessment with Recombined Tools - Objective).

RESULTS

Mean score for objective cognitive functioning was lower than normative values, while mean scores for executive functioning and subjective cognitive functioning were comparable to normative values. There was no relationship between objective and subjective measures. Subjective cognitive functioning and (to a lesser extent) global objective cognitive functioning were significantly associated with mental HRQoL but not with physical HRQoL or social participation.

CONCLUSION

These results underscore the importance of considering both subjective perception and objective performance when assessing and intervening on cognition to promote better mental HRQoL in older adults with TBI.

Dietary Intake of Adult Residents in Luxembourg Taking Part in Two Cross-Sectional Studies-ORISCAV-LUX (2007-2008) and ORISCAV-LUX 2 (2016-2017)

Background: A balanced diet is an important lifestyle component and has been associated with a reduced risk of chronic diseases. Objectives: To assess dietary intake of adult residents in Luxembourg taking part in two population-based cross-sectional studies (ORISCAV-LUX, 2007–2008 and ORISCAV-LUX 2, 2016–2017). Methods: Dietary intake of the study participants (1242 in 2007/08 and 1326 in 2016/17), 25–69 years old, were evaluated using food-frequency questionnaires (134 items in 2007/2008 and 174 items in 2016/2017) according to the French ANSES-CIQUAL food composition database. Both food-group- and nutrient-based analyses were conducted. Results: Dietary patterns in ORISCAV-LUX 2, 2016–2017, were characterized by an increase in the estimated marginal means (EMM) of the intake of energy, total fat, saturated fatty acids, alcohol, and decreased EMM of total carbohydrates, magnesium, and calcium compared to 2007/08. We also observed an increased EMM of the intake of protein-rich food items and ready-to-eat foods/fast foods, together with a decreased intake of grains, dairy products, and vegetables (all p-values <0.05, linear mixed models). The intake of most micronutrients was stable or slightly increased in ORISCAV-LUX 2 vs. ORISCAV-LUX, except for the drop in magnesium and calcium, and generally met recommendations, in particular, EFSA population reference intakes (PRI), except for vitamin D. Conclusions: Though most micronutrient recommendations were met, nutrient consumption in terms of high energy, total fat, and sodium, as well as low carbohydrates, were not aligned with recommendations for balanced eating.

The mechanisms of the protective effect of education in cognitive aging

Frequent cases of pathological brain aging are an important scientific and social problem. Some people have the ability to compensate for the initial manifestations of pathological aging and delay the development of the clinical phenomena of the disease. The concept of “cognitive reserve” allows us to study the possibilities of increasing brain stability in conditions of pathological aging. The identification of the dominant form of thinking, converging or diverging, reveals possible neurophysiological mechanisms of the cognitive reserve. Understanding the mechanisms of formation of individual cognitive styles actualizes the contribution of the “Education” factor to the development of the cognitive reserve. The research material was scientific publications on the topic of work. It was revealed that the “education” factor can realize its protective effect on the pathological aging of the brain due to the formation of an adaptive form of thinking. The data presented in this review make it possible to substantiate the medical and social significance of educational programs for people of mature and older age.

Brain Structure in Bilingual Compared to Monolingual Individuals with Alzheimer's Disease: Proof of Concept

BACKGROUND

Bilingualism is increasingly recognized as protective in persons at risk for Alzheimer's disease (AD).

OBJECTIVE

Compare MRI measured brain volumes in matched bilinguals versus monolinguals with AD.

METHODS

This IRB approved study analyzed T1 volumetric brain MRIs of patients with criteria-supported Probable AD. We identified 17 sequential bilinguals (any native language) with Probable AD, matched to 28 (62%) monolinguals on age and MMSE. Brain volumes were quantified with Neuroreader. Regional volumes as fraction of total intracranial volume (TIV) were compared between both groups, and Cohen's D effect sizes were calculated for statistically significant structures. Partial correlations between bilingualism and brain volumes adjusted for age, gender, and TIV.

RESULTS

Bilinguals had higher brain volumes in 37 structures. Statistical significance (p < 0.05) was observed in brainstem (t = 2.33, p = 0.02, Cohen's D = 0.71) and ventral diencephalon (t = 3.01, p = 0.004, Cohen's D = 0.91). Partial correlations showed statistical significance between bilingualism and larger volumes in brainstem (rp = 0 . 37, p = 0.01), thalamus (rp = 0.31, p = 0.04), ventral diencephalon (rp = 0.50, p = 0.001), and pallidum (rp = 0.38, p = 0.01). Bilingualism positively correlated with hippocampal volume, though not statistically significant (rp = 0.17, p = 0.26). No brain volumes were larger in monolinguals.

CONCLUSION

Bilinguals demonstrated larger thalamic, ventral diencephalon, and brainstem volumes compared to matched monolinguals with AD. This may represent a neural substrate for increased cognitive reserve in bilingualism. Future studies should extrapolate this finding into cognitively normal persons at risk for AD.

Changes in Activity Participation Among Older Adults With Subjective Cognitive Decline or Objective Cognitive Deficits

Participation in daily activities is crucial for healthy aging. There is limited research on participation of older adults with subjective cognitive decline (SCD), defined as the experience of cognitive deficits with no evidence of objective cognitive deficits. Therefore, this study examined perceived changes in participation in this population, and compared it to perceived changes reported by individuals with objective cognitive deficits. The study aimed to: (1) examine the reported changes in activity participation of older with SCD; (2) investigate differences in the reported changes in participation between individuals with SCD and those with mild or severe objective cognitive deficits; (3) examine the relationship between activity participation, subjective memory, and objective cognitive status; and (4) explore whether subjective memory explains additional variance in activity participation after accounting for age and objective cognitive deficits. Participants were 115 older adults (60+), divided into three groups based on their Montreal Cognitive Assessment (MoCA) scores: (1) SCD (MoCA≥26; n = 66); (2) mild objective cognitive deficits (MoCA = 20-25; n = 34); and (3) severe objective cognitive deficits (MoCA ≤ 19; n = 15). The Activity Card Sort was used to measure participation in instrumental activities of daily living, social, and leisure activities. The Multifactorial Memory Questionnaire-Ability subscale was used to assess subjective memory. We found that individuals with SCD, mild cognitive deficits and severe cognitive deficits reported participation withdrawal to a level of 80, 70, and 58% of their past participation, respectively. A significant between group difference was found on participation [χ2(2) = 16.44, p < 0.01], with the SCD group reporting higher participation than the other two groups. Participation significantly correlated with both cognitive status (r = 0.40, p < 0.01) and subjective memory (r = 0.45, p < 0.05). A regression analysis revealed that subjective memory contributed significantly to the explained variance in participation, beyond that accounted for by objective cognitive deficits and age. Our findings demonstrate the important role of subjective memory problems in activity participation of older adults, even in the absence of objective cognitive deficits.

Sino Longitudinal Study on Cognitive Decline (SILCODE): protocol for a Chinese longitudinal observational study to develop risk prediction models of conversion to mild cognitive impairment in individuals with subjective cognitive decline

INTRODUCTION

Understanding the biological mechanism of subjective cognitive decline (SCD) in preclinical Alzheimer's disease (AD) and identifying those who will soon convert to mild cognitive impairment (MCI) are critical for developing appropriate strategies for early diagnosis and intervention of AD. We present the study protocol of the Sino Longitudinal Study on Cognitive Decline (SILCODE), a longitudinal observational study focusing on SCD in the context of AD.

METHODS AND ANALYSIS

Within SILCODE, approximately 800 subjects with SCD who are between 50 and 79 years old will be recruited through standardised public advertisements or memory clinics. They will undergo extensive assessment, including clinical and neuropsychological assessments, blood sample collection for plasma beta-amyloid and ApoE genotype, urine samples collection for AD7c-NTP, and multimodal MRI scans (structural MRI, diffusion tensor imaging, resting-state functional MRI and optional task-based functional MRI) as well as optional glucose metabolism and amyloid positron emission tomography. Subjects will be contacted by telephone every 3 months and interviewed, on average, every 15 months for 5 years. The study endpoint is the development of mild cognitive impairment or dementia. Jak & Bondi's actuarial neuropsychological method will be used for diagnosis of MCI. The least absolute shrinkage and selection operator logistic regression model followed by the sub-distribution hazard function model with death as a competing risk will be constructed to establish risk prediction models.

ETHICS AND DISSEMINATION

The ethics committee of the Xuanwu Hospital of Capital Medical University has approved this study protocol (ID: [2017]046). The results will be published in peer-reviewed journals and presented at national and international scientific conferences.

TRIAL REGISTRATION NUMBER

NCT03370744; Pre-results.

The Association of Perceived Memory Loss with Osteoarthritis and Related Joint Pain in a Large Appalachian Population

Objective

Previous studies have documented memory impairment in several chronic pain syndromes. However, the potential link between memory loss and osteoarthritis (OA), the second most common cause of chronic pain, remains little explored. In this cross-sectional study, we examine the association of perceived memory loss to OA and assess the potential mediating influence of sleep and mood disturbance in a large Appalachian population.

Design

Cross-sectional.

Setting

US Ohio Valley.

Subjects

A total of 21,982 Appalachian adults age 40 years or older drawn from the C8 Health Project (N = 19,004 adults without and 2,478 adults with OA). All participants completed a comprehensive health survey between 2005 and 2006. Medical history, including physician diagnosis of OA, lifestyle factors, short- and long-term memory loss, sleep quality, and mood were assessed via self-report.

Results

After adjustment for demographic, lifestyle, health-related, and other factors, participants with OA were almost three times as likely to report frequent memory loss (adjusted odds ratios [ORs] for short- and long-term memory loss, respectively = 2.7, 95% confidence interval [CI] = 2.2-3.3, and 2.6, 95% CI = 2.0-3.3). The magnitude of these associations increased significantly with rising frequency of reported joint pain (adjusted OR for OA with frequent joint pain vs no OA = 3.3, 95% CI = 2.6-4.1, Ptrend < 0.00001). Including measures of mood and sleep impairment attenuated but did not eliminate these associations (ORs for any memory loss = 2.0, 95% CI = 1.6-2.4, and 2.1, 95% CI = 1.7-2.8, adjusted for sleep and mood impairment, respectively; OR = 1.8, 95% CI = 1.4-2.2, adjusted for both factors).

Conclusions

In this large cross-sectional study, OA and related joint pain were strongly associated with perceived memory loss; these associations may be partially mediated by sleep and mood disturbance.

The dual role of cognitive reserve in subjective cognitive decline and mild cognitive impairment: a 7-year follow-up study

The aim of this study was to evaluate the effect of cognitive reserve (CR), in progression from subjective cognitive decline (SCD) to mild cognitive impairment (MCI) and Alzheimer's disease (AD). For this purpose, we followed up 263 patients (154 SCD; 109 MCI) for a mean time of 7 years. CR was assessed by the Test di Intelligenza Breve (TIB), functionally equivalent to the National Adult Reading Test. High CR resulted as a protective factor for progression from SCD to MCI. Age at conversion to MCI was delayed 9 years on average in SCD with high CR with respect to SCD with low CR. On the contrary, high CR resulted as a risk factor for progression from MCI to AD dementia only in APOE ε4 carriers. Conversion time from MCI to AD dementia was 3 years shorter in ε4 carriers with high CR than subjects with low CR and ε4 non-carriers with high CR. Consistent with the CR hypothesis, our results showed that higher levels of CR protect against the earliest clinical manifestations of AD. In line with the previous researches, we found an interaction between CR and APOE in progression from MCI to AD dementia.

Bilingualism Delays Expression of Alzheimer's Clinical Syndrome

OBJECTIVE

To evaluate the effects of bilingualism on the emergence of Alzheimer's clinical syndrome.

BACKGROUND

Studies have proposed an increase in cognitive and neural reserve from the management and control of two languages, with a consequent delayed expression of dementia.

METHODS

In a clinic with a large immigrant population, we identified 253 patients with probable Alzheimer's disease (AD) with intermediate or high evidence of AD pathophysiological process. These patients were reviewed for demographic variables, native language (L1) other than English, ages of onset and presentation, Mini-Mental State Examination (MMSE), digit spans, word fluencies, naming, and memory.

RESULTS

Among these patients, 74 (29.2%) were bilinguals with various L1s (Farsi, Spanish, Chinese, Tagalog, Arabic, others). When compared to the 179 monolingual AD patients, those who were bilingual had significant delays in ages of onset and presentation of approximately 4 years (p = 0.003). These delays persisted despite bilinguals having worse MMSE scores on presentation. There were no significant group differences on other variables except for worse naming in English among bilinguals versus monolinguals. Caregiver/informants reported that 66 (89.2%) of the 74 bilingual AD patients had gradually regressed to the predominant use of their L1.

CONCLUSIONS

In line with published reports worldwide, we found that bilingualism delays the expression of Alzheimer's clinical syndrome. We also found frequent reversion to the first learned language. These findings suggest that, among bilinguals, the availability of an L1 "back-up" either facilitates compensation or masks emergence of the early symptoms of dementia.

The Luxembourg Parkinson's Study: A Comprehensive Approach for Stratification and Early Diagnosis

While genetic advances have successfully defined part of the complexity in Parkinson's disease (PD), the clinical characterization of phenotypes remains challenging. Therapeutic trials and cohort studies typically include patients with earlier disease stages and exclude comorbidities, thus ignoring a substantial part of the real-world PD population. To account for these limitations, we implemented the Luxembourg PD study as a comprehensive clinical, molecular and device-based approach including patients with typical PD and atypical parkinsonism, irrespective of their disease stage, age, comorbidities, or linguistic background. To provide a large, longitudinally followed, and deeply phenotyped set of patients and controls for clinical and fundamental research on PD, we implemented an open-source digital platform that can be harmonized with international PD cohort studies. Our interests also reflect Luxembourg-specific areas of PD research, including vision, gait, and cognition. This effort is flanked by comprehensive biosampling efforts assuring high quality and sustained availability of body liquids and tissue biopsies. We provide evidence for the feasibility of such a cohort program with deep phenotyping and high quality biosampling on parkinsonism in an environment with structural specificities and alert the international research community to our willingness to collaborate with other centers. The combination of advanced clinical phenotyping approaches including device-based assessment will create a comprehensive assessment of the disease and its variants, its interaction with comorbidities and its progression. We envision the Luxembourg Parkinson's study as an important research platform for defining early diagnosis and progression markers that translate into stratified treatment approaches.

Prevalence, Risk Factors, and Complaints Screening Tool Exploration of Subjective Cognitive Decline in a Large Cohort of the Chinese Population

BACKGROUND

Substantial studies have reported the prevalence and the affecting factors of subjective cognitive decline (SCD). The complaints screening scale has also been used for probing. However, little is known in China.

OBJECTIVE

To investigate the prevalence and risk factors of SCD, and explore an SCD complaints screening scale in China.

METHODS

Stratified cluster random sampling was conducted. 2,689 residents aged 60-80 years completed questionnaire 1. 814 residents were included for clinical and neuropsychological evaluations. Two standards were used to make the diagnosis of mild cognitive impairment (MCI) and SCD, and a preliminary screening rate comparison was carried out. Finally, we assessed the risk factors of SCD and the correlation between the SCD-questionnaire 9 (SCD-Q9) and the Auditory Verbal Learning Test-Long Delay Free Recall (AVLT-LR).

RESULTS

1) Standard 1 (ADNI2): the prevalence of SCD was 18.8% (95% CI = 14.7-22.9%) and zero conformed to six criteria (SCD plus). 2) Standard 2 (Jak/Bondi): the prevalence of SCD was 14.4% (95% CI = 10.7-18.1%). 3) Standard 1 had a relatively higher "false" positive rate, whereas Standard 2 had higher "false" negative rate. 4) Age, low education, fewer close friends, and daily drinking were independent risk factors for SCD progressing to MCI. 5) Total points of SCD-Q9 were negatively correlated to the value of AVLT-LR.

CONCLUSIONS

The prevalence of SCD is high in the ShunYi District in Beijing, China. Age, low education, less social support, and daily drinking are independent risk factors. The brief SCD-Q9 can be used as a reference.

A Systematic Review and Meta-Analysis on the Prevalence of Dementia in Europe: Estimates from the Highest-Quality Studies Adopting the DSM IV Diagnostic Criteria

BACKGROUND

Dementia, including Alzheimer's disease (AD), is one of the most burdensome medical conditions. Usually, the reviews that aim at calculating the prevalence of dementia include estimates from studies without assessing their methodological quality. Alzheimer's Disease International (ADI) proposed a score to assess the methodological quality of population-based studies aimed at estimating the prevalence of dementia. During the last three years, the European Commission has funded three projects (Eurodem, EuroCoDe, and ALCOVE) in order to estimate the prevalence of dementia in Europe.

OBJECTIVE

The aim of this study was to perform a systematic review and meta-analysis of data on the prevalence of dementia in Europe derived from studies that included only subjects with a diagnosis of dementia according to the DSM IV criteria, and that had a high quality score according to ADI criteria.

METHODS

We considered the studies selected by the two projects EuroCoDe (1993-2007) and Alcove (2008-2011), and we performed a new bibliographic search. For the systematic review, we only selected the subset of articles that included subjects with a diagnosis of dementia according to the DSM IV criteria. The studies were qualitatively assessed using the ADI tool.

RESULTS

The meta-analysis considered 9 studies that were carried out in Europe between 1993 and 2018 including a total of 18,263 participants, of which 2,137 were diagnosed with dementia. The prevalence rate standardized for age and sex resulted 7.1%.

DISCUSSION

This is the first systematic review on the prevalence of dementia in Europe considering only high-quality studies adopting the same diagnostic criteria (i.e., DSM IV).