Vijay Chandra

Incidence of Alzheimer’s disease in a rural community in India: The Indo–US Study

Objective: To determine overall and age-specific incidence rates of AD in a rural, population-based cohort in Ballabgarh, India, and to compare them with those of a reference US population in the Monongahela Valley of Pennsylvania. Methods: A 2-year, prospective, epidemiologic study of subjects aged ≥55 years utilizing repeated cognitive and functional ability screening, followed by standardized clinical evaluation using the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, and the National Institute of Neurological and Communicative Disorders and Stroke–Alzheimer’s Disease and Related Disorders Association criteria for the diagnosis, and the Clinical Dementia Rating scale for the staging, of dementia and AD. Results: Incidence rates per 1000 person–years for AD with CDR ≥0.5 were 3.24 (95% CI: 1.48–6.14) for those aged ≥65 years and 1.74 (95% CI: 0.84–3.20) for those aged ≥55 years. Standardized against the age distribution of the 1990 US Census, the overall incidence rate in those aged ≥65 years was 4.7 per 1000 person–years, substantially lower than the corresponding rate of 17.5 per 1000 person–years in the Monongahela Valley. Conclusion: These are the first AD incidence rates to be reported from the Indian subcontinent, and they appear to be among the lowest ever reported. However, the relatively short duration of follow-up, cultural factors, and other potential confounders suggest caution in interpreting this finding.

Prevalence of Alzheimer's disease and other dementias in rural India: the Indo-US study.

Objective: To determine the prevalence of AD and other dementias in a rural elderly Hindi-speaking population in Ballabgarh in northern India. Design: The authors performed a community survey of a cohort of 5,126 individuals aged 55 years and older, 73.3% of whom were illiterate. Hindi cognitive and functional screening instruments, developed for and validated in this population, were used to screen the cohort. A total of 536 subjects (10.5%) who met operational criteria for cognitive and functional impairment and a random sample of 270 unimpaired control subjects (5.3%) underwent standardized clinical assessment for dementia using the Diagnostic and Statistical Manual of Mental Disorders-fourth edition diagnostic criteria, the Clinical Dementia Rating Scale (CDR), and National Institute of Neurological and Communicative Disorders and Stroke-Alzheimers Disease and Related Disorders Association (NINCDS-ADRDA) criteria for probable and possible AD. Results: We found an overall prevalence rate of 0.84% (95% CI, 0.61 to 1.13) for all dementias with a CDR score of at least 0.5 in the population aged 55 years and older, and an overall prevalence rate of 1.36% (95% CI, 0.96 to 1.88) in the population aged 65 years and older. The overall prevalence rate for AD was 0.62% (95% CI, 0.43 to 0.88) in the population aged 55+ and 1.07% (95% CI, 0.72 to 1.53) in the population aged 65+. Greater age was associated significantly with higher prevalence of both AD and all dementias, but neither gender nor literacy was associated with prevalence. Conclusions: In this population, the prevalence of AD and other dementias was low, increased with age, and was not associated with gender or literacy. Possible explanations include low overall life expectancy, short survival with the disease, and low age-specific incidence potentially due to differences in the underlying distribution of risk and protective factors compared with populations with higher prevalence.

Clinical risk factors for Alzheimer's disease A population‐based case‐control study

Using information on clinical risk factors provided through the medical record linkage system of the Rochester Epidemiology Project, we conducted a population-based case-control study of Alzheimers disease (AD). During the period 1960 to 1974, we identified 415 newly diagnosed cases of AD among residents of Rochester, Minnesota, and matched one community control to each case based on age, sex, and duration of community medical record. We estimated odds ratios using conditional logistic regression for several potential clinical risk factors for AD. Among more than 20 clinical risk factors that were evaluated, the only statistically significant findings were for episodic depression, personality disorder, and hypertension.

Cognitive Test Performance in a Community-Based Nondemented Elderly Sample in Rural India: The Indo-U.S. Cross-National Dementia Epidemiology Study

Interpretation of cognitive test performance among individuals from a given population requires an understanding of cognitive norms in that population. Little is known about normative test performance among elderly illiterate non-English-speaking individuals. An age-stratified random sample of men and women, aged 55 years and older, was drawn from a community-based population in the rural area of Ballabgarh in northern India. These Hindi-speaking individuals had little or no education and were largely illiterate. A battery of neuropsychological tests, specially adapted from the CERAD neuropsychological battery, which was administered to this sample, is described. Subjects also underwent a protocol diagnostic examination for dementia. Norms for test performance of 374 nondemented subjects on these tests are reported across the sample and also by age, gender, and literacy.

Trends in incidence of dementing illness in Rochester, Minnesota, in three quinquennial periods, 1960–1974

We ascertained the incidence of dementias of all causes between 1960 and 1975 among citizens of Rochester, Minnesota. Study of all medical records yielded incidence rates for the quinquennial periods of 1960–1964, 1965–1969, and 1970–1974. In the population at risk (30 years or older), the age-adjusted rates (per 100,000 population/year) for Alzheimers disease (clinically diagnosed or pathologically confirmed, or both) in the three periods were: 104.9, 80.8, and 96.6. The rates for dementia of all causes were: 160.6, 122.0, and 136.8. Calculation of 95% confidence intervals showed that the incidence rate for dementia or Alzheimers disease has not changed in this 15-year period in Rochester, Minnesota. Assuming no demented patients younger than 29 years, the incidence rates in the three quinquennial periods for all dements were 79.4, 60.3, and 67.7; for Alzheimers disease they were 51.9, 40.0, and 47.8.

Effects of Literacy and Education on Measures of Word Fluency

As part of a cross-national study of dementia epidemiology, two types of verbal fluency tasks were administered to three groups of subjects, varying in level of literacy and education, recruited from the rural district of Ballabgarh in northern India. Subjects were asked to list items in a given semantic category (animals; fruits) or words beginning with a given sound (the phonemes /p/ and /s/) the latter being a minor modification of the more familiar initial letter fluency task in view of the high prevalence of illiteracy in Ballabgarh. Analysis of variance revealed main effects of education and task with a task by education interaction such that education had a greater effect on initial sound fluency than on category fluency. The results are discussed in terms of their implication for the design of cross-cultural studies and the evidence that the ability to segment speech into phonemic units is dependent on literacy.

Conditions associated with Alzheimer's disease at death Case‐control study

To determine which conditions may be associated with reduced survival in patients with Alzheimers disease, we studied all death certificates in the United States for 1978 on which senile and presenile dementia (ICDA 290, N = 7,195) was mentioned. Each case was compared with two control deaths. Differences in the frequency of listing on the death certificates for the following conditions reached statistical significance: infections, trauma, nutritional deficiency, chronic ulcer of skin, foreign body in pharynx, cataract, glaucoma, blindness, deafness, Parkinsons disease, and epilepsy. There seem to be many preventable and treatable disorders in patients with senile and presenile dementia.

Depressive symptoms, cognitive impairment and functional impairment in a rural elderly population in India: a Hindi version of the geriatric depression scale (GDS-H)

Objective To measure depressive symptomatology in a largely illiterate elderly population in India, using a new Hindi version of the Geriatric Depression Scale (GDS-H), and to examine its distribution and associations with age, gender, literacy, cognitive impairment and functional impairment. Design A Hindi version of the Geriatric Depression Scale was developed and administered to participants along with measures of demographic characteristics, cognitive functioning and functional ability. Setting The rural community of Ballabgarh in northern India. Participants A community sample of 1554 mostly illiterate Hindi-speaking residents of Ballabgarh aged 55+. Measures The Hindi version of the Geriatric Depression Scale (GDS-H); the Hindi Mental State Exam (HMSE); the Everyday Abilities Scale for India (EASI); age, gender and literacy. Results The GDS-H had high internal consistency and a factor structure comparable to the original English language version. The overall distribution of scores was higher than reported from other populations. Greater numbers of depressive symptoms, as measured by higher scores on the GDS-H, were associated with older age and illiteracy. Among the illiterate, there was no gender difference while among the literate, higher GDS-H scores were found among women. Cognitive impairment and functional disability were independently associated with higher scores on the GDS-H after adjustment for age, gender and literacy. Conclusion A reliable and valid Hindi version of the GDS has been developed. Depressive symptoms as measured by the GDS-H were prominent in this elderly illiterate northern Indian population and strongly associated with both cognitive and functional impairment. Copyright

Head trauma with loss of consciousness as a risk factor for Alzheimer's disease

We identified all incident cases of clinically diagnosed Alzheimers disease among the population of Rochester, MN, with onset from 1965 through 1974. A control (selected from the same community) was matched to each case by age, race, sex, and length of stay in Rochester. We studied 274 case-control pairs. Using the records linkage system available for residents of this community, we abstracted information on the occurrence of head trauma with loss of consciousness (LOC) from the medical records of both cases and controls. There were 5 pairs in which the case suffered an episode of head trauma with LOC but the control did not, and 4 pairs in which the control suffered an episode of head trauma with LOC but the case did not. We failed to detect a statistically significant difference between the 2 groups. This study overcomes many problems encountered in previous case-control studies reporting this association. The sample size was large; severity of head injury was documented in high-quality medical records; data about head injury were recorded before the onset of dementia; equal quality of data were available for cases and controls; and, since the study was population-based, there was no selection bias for cases or controls.

Gene-Environment Interaction in Alzheimer’s Disease:A Potential Role for Cholesterol

Alzheimer’s disease is probably a complex disease caused by an interaction of multiple environmental and genetic factors. Genetic defects include ‘causative’ genes which are rare and a ‘susceptibility’ gene (σ4 allele of apolipoprotein E) which is more common in cases. Recent research suggests that environmental factors may interact with a genetic predisposition to modify the risk of Alzheimer’s disease. An interaction between serum cholesterol levels and σ4 genotype is proposed. The evidence for this gene-environment interaction is discussed.