Anja Busse

Mild cognitive impairment: a review of prevalence, incidence and outcome according to current approaches

Objective:  Mild cognitive impairment is associated with an increased risk of developing dementia. However, agreement needs to be reached on clearly specified diagnostic criteria for mild cognitive impairment. The present paper critically reviews the different constructs of mild cognitive impairment on the basis of the available empirical evidence.

Subclassifications for mild cognitive impairment: prevalence and predictive validity.

BACKGROUND Mild cognitive impairment (MCI) is associated with an increased risk of developing dementia. Recently published results of the Current Concepts in MCI Conference suggested subclassifications for MCI (MCI-amnestic, MCI-multiple domains slightly impaired, MCI-single nonmemory domain) based on the recognized heterogeneity in the use of the term. These subclassifications have not been empirically validated to date. METHOD A community sample of 1045 dementia-free individuals aged 75 years and over was examined by neuropsychological testing in a three-wave longitudinal study. The prevalences and the predictive validities for the subclassifications of MCI and their modifications (original criteria except for the report of subjective decline in cognitive function) were determined. RESULTS The prevalence was 1 to 15% depending on the subset employed. Subjects with a diagnosis of MCI progressed to dementia at a rate of 10 to 55% over 2.6 years, depending on the subset employed. MCI-amnestic achieved the highest positive predictive power (PPP). ROC curves of the subclassifications for MCI indicate that all but one subset for MCI failed to predict dementia (MCI-multiple domains slightly impaired-modified: AUC=0.585, P<0.01, 95% CI, 0.517-0.653). The use of modified criteria for MCI (original criteria except for the report of subjective decline in cognitive function) is associated with a higher diagnostic sensitivity but also with a reduction in diagnostic specificity and PPP. CONCLUSIONS Modified criteria should be applied if a concept for MCI with a high sensitivity is required and the original criteria (including subjective cognitive complaint) if a concept with high specificity and high PPP is required.

The state of mental health in old-age across the old European Union - a systematic review

Objective:  The paper provides the first syllabus on the prevalence of mental disorders in old‐age focusing on surveys conducted in the 15 countries, which comprised the ‘old’ European Union.

Mild cognitive impairment1: prevalence and predictive validity according to current approaches

Objectives – Mild cognitive impairment is associated with an increased risk of developing dementia. However, there is no consensus on diagnostic criteria and different concepts have rarely been evaluated in population‐based samples. This paper compares the prevalences and predictive validities for different concepts in a population‐based study. The aim was to identify a concept with the best relation of sensitivity and specificity in the prediction of dementia.

Adaptation of dementia screening for vision-impaired older persons: Administration of the Mini-Mental State Examination (MMSE)

In epidemiologic field studies on the prevalence and incidence of dementia the problems associated with the cognitive testing of visually impaired individuals are rarely discussed. In the Leipzig Longitudinal Study of the Aged (LEILA 75+) a version of the Mini-Mental State Examination for the visually impaired (MMSE-blind) was employed from which all items requiring image processing had been omitted. To be able to interpret the test results and include vision-impaired individuals in the field study, the scores for the full MMSE were estimated by conducting linear transformation of the scores obtained on the MMSE-blind. The method of linear transformation is based on certain theoretical assumptions that are examined in this article. Linear transformation of scores has proved to be a valid procedure only for individuals with very high or very low cognitive performance. Thus, evaluation of the estimated full MMSE scores based on the norms for the original MMSE is not recommended. A blind version of the MMSE with age- and education-specific norms that has been validated as a screening tool for dementia is therefore presented.

Prävalenz und Inzidenz von Demenzerkrankungen in Alten- und Altenpflegeheimen im Vergleich mit Privathaushalten*

Zusammenfassung. Im Rahmen einer aktuellen repräsentativen epidemiologischen Untersuchung der über 75-jährigen Altenbevölkerung von 1997–1999 wurden Prävalenz- und Inzidenzraten dementieller Erkrankungen in Alten- und Altenpflegeheimen (n=192) ermittelt und mit Privathaushalten (n=1500) verglichen. Die kognitive Leistungsfähigkeit wurde mit dem SIDAM (Strukturiertes Interview zur Diagnose der Demenz vom Alzheimer-Typ, Multiinfarkt-Demenz und Demenzen anderer Ätiologie nach DSM-III-R und ICD-10) erhoben. Für Studienteilnehmer, die aufgrund schwerer gesundheitlicher Beeinträchtigungen nicht mit diesem Verfahren getestet werden konnten bzw. vor der Folgeuntersuchung verstarben, wurde die kognitive Leistung mit dem CDR (Clinical Dementia Rating) im Rahmen eines strukturierten Interviews mit Angehörigen bzw. dem Pflegepersonal eingeschätzt. Sowohl die Prävalenz- als auch die Inzidenzraten dementieller Erkrankungen sind für die Heimbewohner etwa viermal höher als für Personen in Privathaushalten. Für die über 75-jährigen Heimbewohner wurde eine Prävalenzrate dementieller Erkrankungen nach DSM-III-R von 47,6% sowie eine jährliche Inzidenzrate von 17,2% ermittelt. Der hohe Anteil an demenzerkrankten Bewohnern erfordert, die Konzepte der Pflege in den Heimen zu überdenken und der veränderten Situation anzupassen.Summary. Based on a representative epidemiological study on dementia, prevalence and incidence rates of institutionalized individuals aged 75 years and older in comparison to those living in private homes are presented. The study was conducted between 1997 and 1999. Core component assessing cognitive function was the SIDAM (Structured Interview for the diagnosis of Dementia of the Alzheimer type, Multi-infarct dementia and dementias of other etiology according to ICD-10 and DSM-III-R, DSM-IV). If cognitive testing with study participants was not possible (e.g., due to fragility, death before examination) proxy interviews were performed with relatives or staff using the CDR (Clinical Dementia Rating). Prevalence and incidence rates in institutions were four times higher than in private homes. A prevalence rate of dementia for institutionalized individuals 75+ according to DSM-III-R of 47.6% was found; the annual incidence rate was 17.2%. This high proportion of people with dementia in institutions requires the development of new concepts of care to meet the demands of this changing situation in residential and nursing homes.

Are cognitively impaired individuals adequately represented in community surveys? Recruitment challenges and strategies to facilitate participation in community surveys of older adults. A review

Background: Dementia is the most important age-related disorder and subject to a substantial body of epidemiological research. However, field work in elderly populations faces special challenges which may reduce response rates and invalidate survey results. Therefore, this paper will review more recent prevalence studies of dementia to examine how recruitment issues and their influence on the study outcome have been addressed. Methods: Field studies of the elderly with the main focus on prevalence of dementia published over the last 10 years will be systematically reviewed. The review concerns sampling frames, ways to include institutionalised individuals, response rates and strategies to deal with special challenges of field work in elderly populations such as mortality, fragility and sensory impairment. Furthermore, papers were evaluated regarding the extent to which recruitment outcomes were discussed. Results: The literature is characterised by a disregard of recruitment issues to a varying extent. Mortality, functional dependency and sensory impairment (all positively related to dementia) are barely taken into account in the study design and rarely discussed. As a consequence, cognitively impaired individuals are likely to be underrepresented in most community studies. Conclusion: Strategies to deal with special challenges of field work in the elderly in a systematic manner and to facilitate participation in population surveys of the elderly are crucial and will be outlined. Communication on recruitment issues is essential to improve the validity of study outcomes.

Mortality in Individuals with Mild Cognitive Impairment

Objective: This study aimed to investigate whether mortality is higher for individuals suffering from Mild Cognitive Impairment (MCI). Methods: A community sample of 1,045 dementia-free individuals aged 75 years and over was examined using neuropsychological tests over a 4.5-year period. Data were analyzed with the Cox proportional hazards model after having been adjusted for age, gender, and incident dementia. Results: Association between MCI and mortality was examined subject to varied diagnostic criteria of MCI. We found an increased risk of death that was about 1.5 times higher for individuals with MCI when a cognitive performance of more than 1.5 standard deviation below the mean of age- and education-matched controls was required and the criterion of a cognitive complaint was excluded. Males were at about a 40% increased risk of death. Risk also increased with age by about 8% per year. Incident dementia showed a significant influence on mortality only if it became manifest by 1.5 years after the baseline measurement (follow-up 1). Conclusion: MCI is associated with increased mortality when certain diagnostic criteria are applied.

Alters- und bildungsspezifische Normierung des kognitiven Tests des SIDAM

Zusammenfassung. Das SIDAM (Strukturiertes Interview zur Diagnose der Demenz vom Alzheimer-Typ, Multiinfarkt-Demenz und Demenzen anderer Ätiologie nach DSM-IV und ICD-10) ist ein standardisiertes Interview zur Demenzdiagnose, das neben dem Einsatz als Screeninginstrument auch die Diagnose unterschiedlicher Demenzsyndrome sowie leichter kognitiver Beeinträchtigung ermöglicht. Eine alters- oder bildungsspezifische Normierung des Testverfahrens liegt bislang nicht vor. Es werden alters- und bildungsspezifische Referenzwerte für den kognitiven Leistungsteil des SIDAM vorgestellt, die auf der Grundlage einer bevölkerungsrepräsentativen Stichprobe (n=1001) der über 75-jährigen Altenbevölkerung ermittelt wurden.Summary. The SIDAM (Structured Interview for the diagnosis of Dementia of the Alzheimer type, Multi-infarct dementia and dementias of other etiology according to ICD-10 and DSM-IV) is a standardized interview for the diagnosis of dementia. It can also be used as a screening instrument for the diagnosis of different syndromes of dementia and mild cognitive impairment. At present there is no age- or education-specific standardization. This report presents age- and education-specific norms for the cognitive assessment of the SIDAM, obtained in a population-based sample of elderly people aged 75 and over (n=1001).

Mild Cognitive Impairment and Development of Dementia

OBJECTIVE In order to identify mildly cognitively impaired subjects, MILD COGNITIVE IMPAIRMENT: (MCI) represents a current and well-discussed concept. Prevalence and conversion rates, relative risks and data on the sensitivity and specifity of MCI for the development of dementia will be calculated. METHODS 980 subjects aged 75 years and over who participated in the Leipzig Longitudinal Study of the Aged (LEILA 75+) were clinically interviewed and cognitively tested at regularly intervals over a mean period of six years. RESULTS At baseline, the prevalence of MCI was 19.3 %, including (original) and 41.5 % excluding (modified) the criterion of subjective cognitive complaints. Diagnoses of original and modified amnestic MCI-subtypes were associated with relative risks of more than three for the development of dementia. CONCLUSIONS MCI represents a risk factor for dementia, mainly if the cognitive impairments are related to the area of memory. However, in order to predict dementia reliably, further findings (e. g. biomarkers) are required.