Olusegun Baiyewu

Prevalence of cognitive impairment Data from the Indianapolis Study of Health and Aging

Background: The epidemiology and natural history of cognitive impairment that is not dementia is important to the understanding of normal aging and dementia. Objective: To determine the prevalence and outcome of cognitive impairment that is not dementia in an elderly African American population. Method: A two-phase, longitudinal study of aging and dementia. A total of 2212 community-dwelling African American residents of Indianapolis, IN, aged 65 and older were screened, and a subset (n = 351) received full clinical assessment and diagnosis. Subsets of the clinically assessed were seen again for clinical assessment and rediagnosis at 18 and 48 months. Weighted logistic regression was used to generate age-specific prevalence estimates. Results: The overall rate of cognitive impairment among community-dwelling elderly was 23.4%. Age-specific rates indicate increasing prevalence with increasing age: 19.2% for ages 65 to 74 years, 27.6% for ages 75 to 84 years, and 38.0% for ages 85+ years. The most frequent cause of cognitive impairment was medically unexplained memory loss with a community prevalence of 12.5%, followed by medical illness–associated cognitive impairment (4.0% prevalence), stroke (3.6% prevalence), and alcohol abuse (1.5% prevalence). At 18-month follow-up, 26% (17/66) of the subjects had become demented. Conclusions: Cognitive impairment short of dementia affects nearly one in four community-dwelling elders and is a major risk factor for later development of dementia.

Cholesterol, APOE genotype, and Alzheimer disease: An epidemiologic study of Nigerian Yoruba

Objective: To examine the relationship between cholesterol and other lipids, APOE genotype, and risk of Alzheimer disease (AD) in a population-based study of elderly Yoruba living in Ibadan, Nigeria. Methods: Blood samples and clinical data were collected from Yoruba study participants aged 70 years and older (N = 1,075) as part of the Indianapolis-Ibadan Dementia Project, a longitudinal epidemiologic study of AD. Cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglyceride levels were measured in fasting blood samples. DNA was extracted and APOE was genotyped. Diagnoses of AD were made by consensus using National Institute of Neurologic Disorders/Stroke-Alzheimers Disease and Related Disorders Association criteria. Results: Logistic regression models showed interaction after adjusting for age and gender between APOE-ε4 genotype and biomarkers in the risk of AD cholesterol*genotype (p = 0.022), LDL*genotype (p= 0.018), and triglyceride*genotype (p = 0.036). Increasing levels of cholesterol and LDL were associated with increased risk of AD in individuals without the APOE-ε4 allele, but not in those with APOE-ε4. There was no significant association between levels of triglycerides and AD risk in those without APOE-ε4. Conclusions: There was a significant interaction between cholesterol, APOE-ε4, and the risk of Alzheimer disease (AD) in the Yoruba, a population that has lower cholesterol levels and lower incidence rates of AD compared to African Americans. APOE status needs to be considered when assessing the relationship between lipid levels and AD risk in population studies.

APOE ε4 is not associated with Alzheimer's disease in elderly Nigerians

Since 1992, research teams from Indiana University and the University of Ibadan have been collecting and comparing data from two diverse, elderly populations to identify risk factors for dementia and Alzheimers disease. Apolipoprotein E (APOE) was genotyped in 2,245 Nigerian samples. Of these, 830 had a diagnosis: 459 were normal, and 140 had dementia including 123 diagnosed with Alzheimers disease. In contrast with other populations, the APOE ε4 allele was not significantly associated with Alzheimers disease or dementia. This lack of association in the Yoruba might reflect genetic variation, environmental factors, as well as genetic/environmental interactions. Ann neurol 2006

Epidemiology of dementia in Nigeria: results from the Indianapolis-Ibadan study.

We determined the prevalence of dementia in a cohort of 2494 elderly Nigerians residents in Idikan Community, Ibadan, Nigeria. We utilized the Community Screening Instrument for Dementia to select subjects for clinical assessment in the second stage. The findings were compared with those of 2212 African Americans living in Indianapolis, studied simultaneously using similar methodology. The overall age‐adjusted prevalence rates of dementia and Alzheimers disease in Ibadan were 2.29% and 1.41%, respectively. These rates were much lower than the respective values of 8.24% and 6.24% obtained for African Americans. In Ibadan, Alzheimers disease accounted for 64.3% of the cases, with old age and female gender being the significant risk factors, whilst ‘living with others’ appeared to be protective (P < 0.05). Amongst African Americans, on the other hand, old age, rural living below the age of 19 years, low educational attainment and family history of dementia were the risk factors. There was a lack of association between Alzheimers disease and possession of the apolipoprotein E ε4 allele in the Nigerian sample, unlike the finding in African Americans, where significant association was shown. In addition, the frequencies of the vascular risk factors investigated were lower in Nigerians.

Prevalence rates for dementia and Alzheimer's disease in African Americans: 1992 versus 2001.

This study compares age‐specific and overall prevalence rates for dementia and Alzheimers disease (AD) in two nonoverlapping, population‐based cohorts of elderly African Americans in Indianapolis in 2001 and 1992.

The Stick Design test: A new measure of visuoconstructional ability

Visuoconstructional ability is an important domain for assessment in dementia. Use of graphomotor measures dominate this area; however, participants with low education produce results that cannot be easily interpreted. Our objective was to develop and validate a nongraphomotor assessment of visuoconstructional ability for use in dementia evaluations in persons with low or no education. In a longitudinal, population-based study of dementia among Yoruba residents of Ibadan, Nigeria aged 65 years and older, participants underwent clinical assessment with a battery of cognitive tests and consensus diagnosis. Performance on two visuoconstructional tests, Constructional Praxis and Stick Design, were compared. Gender, age, and education affected performance on both tests. The Stick Design test was more acceptable than Constructional Praxis as measured by the number of participants with total test failure (3.9% vs. 15.1%). The Stick Design test was significantly more sensitive to cognitive impairment and dementia than the Constructional Praxis test. We conclude that Stick Design is a reasonable test of visuoconstructional ability in older cohorts with very limited educational exposure and literacy.

Behavioral and Caregiver Reaction of Dementia as Measured by the Neuropsychiatric Inventory in Nigerian Community Residents

BACKGROUND The Neuropsychiatric Inventory (NPI) has been used to assess behavioral symptoms of dementia in the United States, Taiwan, Japan, and Italy. METHOD This report evaluates the use of the NPI to assess behavioral symptoms of dementia in a population of Yoruba, Nigerians aged 65 years and older who are subjects in the Indianapolis-Ibadan Dementia Project. In this study, the NPI, Blessed Dementia Scale, and Mini-Mental State Examination (MMSE) were used to assess Nigerian subjects with dementia. For this study the NPI was translated, back translated, and harmonized into Yoruba. RESULTS The harmonized version of the NPI showed good interrater and test-retest reliability. The Cronbach alpha on 40 subjects was .80 for total severity score, .73 for frequency, and .73 for distress, indicating good internal consistency. The MMSE correlated with the NPI total score and severity scores of delusion, hallucination, and agitation, whereas the Blessed correlated with the NPI total score and severity scores of depression, anxiety, and nighttime behavior. CONCLUSIONS The NPI was found to be a reliable tool to assess behavioral symptoms and caregiver distress of dementia in the Yoruba. Behavioral disturbances were as common in the Yoruba patients with dementia as in studies in other countries that have used the NPI, but the pattern of behavioral disturbances and caregiver response varied among the countries.

Mild Cognitive Dysfunction : An Epidemiological Perspective With an Emphasis on African Americans

This review begins with a historical accounting of the evolution of the concept of mild cognitive dysfunction, including nomenclature and criteria from Kral to Petersen. A critical analysis of the main elements relating to assessment and diagnosis of mild cognitive dysfunction is provided. Methodological limitations in design, measurement, and characterization, especially as they relate to older African Americans, are identified. Data from a 15-year longitudinal study of community-dwelling African Americans in Indianapolis, Indiana, indicate a 23% prevalence of all-cause mild cognitive dysfunction, with approximately 25% progressing to dementia in 2 years and another 25% reverting to normal cognition in the same interval. Factors contributing to this longitudinal variability in outcomes are reviewed, including the role of medical health factors. The review closes with suggestions for next steps in the epidemiological research of mild cognitive impairment. (J Geriatr Psychiatry Neurol 2007;20:215—226)

The development of a semi-structured home interview (CHIF) to directly assess function in cognitively impaired elderly people in two cultures.

BACKGROUND Assessing function is a crucial element in the diagnosis of dementia. This information is usually obtained from key informants. However, reliable informants are not always available. METHODS A 10-item semi-structured home interview (the CHIF, or Clinician Home-based Interview to assess Function) to assess function primarily by measuring instrumental activities of daily living directly was developed and tested for inter-rater reliability and validity as part of the Indianapolis-Ibadan dementia project. The primary validity measurements were correlations between scores on the CHIF and independently gathered scores on the Blessed Dementia Scale (from informants) and the Mini-mental State Examination (MMSE). Sensitivities and specificities of scores on the CHIF and receiver operator characteristic (ROC) curves were constructed with dementia as the dependent variable. RESULTS Inter-rater reliability for the CHIF was high (Pearsons correlation coefficient 0.99 in Indianapolis and 0.87 in Ibadan). Internal consistency, in both samples, was good (Cronbachs alpha 0.95 in Indianapolis and 0.83 in Ibadan). Scores on the CHIF correlated well with the Blessed Dementia scores at both sites (-0.71, p < 0.0001 for Indianapolis and -0.56, p < 0.0001 for Ibadan) and with the MMSE (0.75, p < 0.0001 for Indianapolis and 0.44, p < 0.0001 for Ibadan). For all items at both sites, the subjects without dementia performed significantly better than those with dementia. The area under the ROC curve for dementia diagnosis was 0.965 for Indianapolis and 0.925 for Ibadan. CONCLUSION The CHIF is a useful instrument to assess function directly in elderly participants in international studies, particularly in the absence of reliable informants.

Prevalence of dementia and dementia subtypes among community-dwelling elderly people in northern Nigeria.

BACKGROUND Dementia has important public health implications. The magnitude of the problem remains largely unknown in the developing countries. METHODS Three hundred and twenty-two community dwelling elderly persons and their caregivers in Zaria, Northern-Nigeria were enrolled in this study. They were interviewed using Community Screening Interview for Dementia (CSI-D), Consortium to Establish Registry for Alzheimers disease (CERAD), Stick Design Test (SDT), Blessed Dementia Scale and a sociodemographic questionnaire. The data obtained were analyzed using the Statistical Package for Social Sciences version 15 for Windows. Diagnosis was based on fulfilling criteria for dementia in both the International Classification of Disease, 10th edition and the Diagnostic and Statistical Manual, 4th edition. RESULTS The mean age of the subjects was 75.5 ± 9.4 years. The prevalence of dementia was 2.79% (CI 1-4.58%). Alzheimers disease constituted 66.67% of all the cases of dementia in this community. Age was the only demographic factor associated with dementia. CONCLUSION The prevalence rates of dementia and dementia subtypes in the developing countries are similar using standard diagnostic criteria and methods.