Projections of Alzheimer's disease in the United States and the public health impact of delaying disease onset

Methods for projecting the incidence and prevalence of chronic diseases in aging populations: application to Alzheimer's disease

Projections of the incidence and prevalence of disease are important for public health planning. This paper describes methods for projecting the incidence and prevalence of a chronic disease in ageing populations. The approach uses age-specific disease incidence rates together with assumptions about survival to reconstruct disease prevalence. The methods can be used to evaluate the potential impact of public health interventions that may prevent disease or prolong survival. We used the methods to project the future prevalence of Alzheimer's disease in the United States. We found that the prevalence of Alzheimer's disease will nearly quadruple over the next 50 years. Although projections of the absolute prevalence are sensitive to assumptions about the age-specific incidence rates of disease, the proportionate growth is relatively insensitive. The increase in prevalence results from the ageing of the U.S. population. In order to perform the calculations, we have assembled U.S. Census population projections and U.S. mortality rates into computer software that is available from the authors at www.jhsph.edu/Departments/Biostats/software.h tml.

Age-specific incidence rates of Alzheimer's disease: the Baltimore Longitudinal Study of Aging

OBJECTIVE

To estimate age-specific incidence rates of AD in the Baltimore Longitudinal Study of Aging (BLSA).

BACKGROUND

The BLSA is a volunteer cohort of normal subjects followed longitudinally with biennial evaluations at the Gerontology Research Center of the National Institute on Aging.

METHODS

Subjects are 1236 participants (802 men, 434 women) in the BLSA with longitudinal follow-up between January 1985 and May 1998. The average length of follow-up was 7.5 years, with participants evaluated every 2 years by physical, neurologic, and neuropsychological examinations. Using Diagnostic and Statistical Manual of Mental Disorders, 3rd ed., revised and National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria, the authors diagnosed dementia and AD.

RESULTS

The authors diagnosed 155 cases of dementia, of which 114 (74%) were AD. Incidence rates of AD increased with age from an estimated 0.08% per year (95% CI 0.00 to 0.43) in the 60 to 65 age group to an estimated 6.48% per year (95% CI 5.01 to 8.38) in the 85+ age group for men and women combined. The doubling time of incidence rates was estimated to be approximately 4.4 years and the median time of conversion from mild cognitive impairment to diagnosis of AD was estimated to be 4.4 years. There was a trend for women to have higher incidence rates than men and for fewer years of education to be associated with higher incidence rates; however, these effects were not significant.

CONCLUSION

Incidence rates for AD in the BLSA are consistent with published rates in other studies. The longitudinally followed subjects of the BLSA offer a unique opportunity to prospectively investigate the antecedents of AD.

Self-transcendence and family caregivers of adults with dementia

Research has documented that caring for a family member with dementia is stressful and burdensome. However, difficult life experiences such as fear, loss, and grief may help persons move beyond a concern for self toward a larger perspective and concern for others. Both positive and negative experiences can promote positive movement toward growth and development. This movement has been described as self-transcendence, or the ability to look beyond the self and present difficulties, to extend concern to others, and to find personal meaning and wholeness in the context of life-changing events. The family caregiving experience with its inherent difficulties might provide the impetus for such a movement toward self-transcendence. The purpose of this article is to examine the concept of self-transcendence, explore its linkages to the caregiving experience, and suggest potential strategies to assist family caregivers to achieve self-transcendence.

A long-term, multicenter, open-label study of risperidone in elderly patients with psychosis. On behalf of the Risperidone Working Group

RATIONALE

Studies have shown that risperidone is safe and efficacious in young and middle-aged adults with chronic schizophrenia, but considerably fewer data are available on the treatment of elderly patients with schizophrenia or other psychotic disorders, particularly long-term outcomes.

OBJECTIVE

A 12-month, open-label study was conducted to assess the effects of risperidone in elderly, chronically ill, psychotic patients.

METHODS

This study enrolled 180 elderly, chronically ill, psychotic patients (median age, 72 years [range 54-89]), 97 of whom completed the 12-month study. At endpoint, the mean dose of risperidone was 3.7 mg/day.

RESULTS

Clinical improvement (> or =20% reduction in Positive and Negative Syndrome Score [PANSS] total score) was achieved by 54% of patients at endpoint. There were significant reductions in PANSS total, subscale (positive, negative, and general psychopathology), and cognition cluster scores at endpoint (p<0.001). Clinical Global Impressions severity of illness scores showed continued improvement through month 12 (p<0.001). In contrast, PANSS data from a historical comparable control group of patients receiving conventional antipsychotic agents showed no symptom improvement over a 12-month treatment period. The severity of preexisting extrapyramidal symptoms (EPS) in patients treated with risperidone decreased significantly from baseline to endpoint (p<0.001), and the use of antiparkinsonian medication decreased from 41.1% of patients before the trial to 25.6% during the trial. There were no spontaneous reports of tardive dyskinesia (TD) and the incidence of assessed TD was 4.3% in contrast to the expected 26% reported in middle-aged and elderly patients receiving conventional antipsychotic agents for 1 year.

CONCLUSIONS

Long-term treatment with risperidone was associated with continued symptom improvement, a decrease in the severity of preexising EPS, and a low incidence of TD in elderly psychotic patients.

Medical services utilization and charge comparisons between elderly patients with and without Alzheimer's disease in a managed care organization

OBJECTIVES

The purposes of this study were to describe the health service utilization patterns and the associated charges for elderly patients (aged > or = 65 years) diagnosed with Alzheimer's disease (AD) enrolled in a managed care organization (MCO), and to compare these patterns and charges with those of elderly enrollees not diagnosed with AD (non-AD).

METHODS

We analyzed medical claims data over a 12-month period for the population of elderly patients with a diagnosis of AD or AD-related dementia, and for all other elderly patients enrolled in an integrated MCO. Comparisons were made at the level of service location (eg, inpatient hospital, outpatient hospital, physician's office).

RESULTS

For a total of 250 patients diagnosed with AD (66.0% female, 34.0% male; mean age. 80.5 years), health care charges were 1.6 times higher per patient per year than the corresponding charges for 13,553 non-AD patients (58.6% female, 41.4% male; mean age, 73.3 years). AD patients received 1.7 times more health care services per patient per year than their non-AD counterparts.

CONCLUSIONS

Despite the lack of nursing home and prescription drug data, our results show that AD patients in this MCO used more health care services and had higher annual medical care charges than non-AD patients. If MCOs conduct similar analyses of elderly AD patients' patterns of care and compare these with the patterns of elderly non-AD patients, they may be able to pinpoint areas of disparity in medical care and improve service delivery for AD patients.

[Perception of cognitive deficits and behavior disorders in patients with Alzheimer's disease]

Alzheimer's disease (AD) is associated with cognitive decline and, often, the development of behavioural abnormalities. However, patients may have limited insight into the severity and extent of their impairments. This study was designed to investigate agreement between patients and carers on the assessment of cognitive and behavioural symptoms typically associated with AD. Thirty consecutive outpatients meeting criteria for the diagnosis of AD according to DSM-IV and their respective carers were invited to participate in this study. An enlarged version of the questionnaire for dementia-anosognosia (QD) was used to assess cognitive and behavioural symptoms according to patients and carers. Cognitive impairment was further assessed with the mini-mental state examination (MMSE). The mean age of patients and carers was 71.38 (CI=68.23 to 74.53) and 52.48 (CI=47.11 to 57.86) respectively. Sixty and 73.3% of patients and carers were women. The mean MMSE score for patients was 14.93 (CI=12.68 to 17.18). Agreement between patients and carers for all QD items was assessed using weighted Kappa - rates were low and ranged from 0 to 0.67. Only 3 of the 42 QD items were associated with Kappa values greater than 0.40. The overall score for questions assessing cognitive abilities (QD-A) was significantly lower according to the evaluation of patients than that of carers (paired t-test = -4.07, p<0.001). The same pattern was observed for questions assessing behaviour (QD-B)(paired t-test= -2.27, p=0.032). The Spearman correlation between QD-A and MMSE scores was -0.39 and -0.57 according patients and carers respectively. The association between cognitive anosognosia (difference between QD-A according to carers and patients) and MMSE scores was poor (rho= -0.14). In addition, cognitive anosognosia scores of patients with and without significant depressive symptoms was similar (t= -0.40, p=0.698). These results suggest that AD patients have limited insight into the severity and extent of their cognitive and behavioural problems. In addition, our data shows that this lack of awareness is not influenced by the severity of cognitive impairment or the presence of depressive symptoms.

Do nutrition indicators predict death in elderly Canadians with cognitive impairment?

This study describes the independent association between nutritional risk and death in older adults diagnosed with cognitive impairment. Canadian Study of Health and Aging participants who completed a clinical exam and were diagnosed with cognitive impairment and had complete data for regression analyses were included (n = 735). Nutritional risk was defined as the presence of at least one abnormal nutrition indicator identified during the clinical exam (history of weight loss, abnormal serum albumin, poor appetite, body mass index < 20). Other covariates believed to influence mortality were modelled with nutritional risk using logistic regression. There were 373 deaths during the five-year follow-up period in this sample. Nutritional risk was found to independently increase the likelihood of death (OR = 1.6, 95% CI 1.1, 2.2) in these older adults suffering from cognitive impairment. Further work is required to determine if interventions can improve nutritional status and quality of life of these older adults.

Risk factors for nursing home placement in a population-based dementia cohort

OBJECTIVE

To examine risk factors for nursing home placement in a population-based dementia cohort.

METHODS

The Mayo Clinic Medical Records linkage system was used to identify all patients with onset of dementia between 1980 and 1984. The patient group included 314 cases who met DSM-III-R criteria for dementia, including 220 cases who were community dwelling at onset. All dementia patients were followed until death. A control group included 323 patients who did not, at any point, meet DSM-III-R criterion for dementia. The groups were initially matched on age, gender, and year of initial registration. Demographic, medical, social, and functional predictors were examined as static and time-dependent risk factors for nursing home placement in the initial community-dwelling subgroups, using stepwise Cox regression modeling.

RESULTS

Of the 314 dementia patients, 282 took residence in licensed skilled nursing homes for at least 6 weeks, suggestive of custodial care, at some point during the course of their illness. In the control group, 162 of the 323 people required nursing home placement. Within controls, the predictor variables of time to nursing home placement included initial age, being divorced, living in a townhome, apartment or assisted living apartment, change in Charlson comorbidity score, and change in amount of daily assistance required. Within the dementia sample, seven predictors were eventually determined to be associated with time to nursing home placement. These included total number of years of education, age at onset of dementia, being single, living in a retirement or supervised apartment at onset, change in Charlson comorbidity score, and a change in the amount of daily assistance required.

CONCLUSIONS

Cumulative incidence of placement was 90% in the dementia cohort and 50% in the controls. Certain variables seem to impact time to nursing home placement in all older persons, whether they have dementia or not. Among these are age, living in assisted living settings, increasing comorbidity scores, and increasing need for functional assistance. Certain additional factors may have a specific impact in dementia. Among these is education, which seems to provide a protective effect. These predictors may be important covariates in clinical dementia studies that include time to nursing home placement as an outcome variable.

Fine mapping of the chromosome 12 late-onset Alzheimer disease locus: potential genetic and phenotypic heterogeneity

Apolipoprotein E (APOE) is the only confirmed susceptibility gene for late-onset Alzheimer disease (AD). In a recent genomic screen of 54 families with late-onset AD, we detected significant evidence for a second late-onset AD locus located on chromosome 12 between D12S373 and D12S390. Linkage to this region was strongest in 27 large families with at least one affected individual without an APOE-4 allele, suggesting that APOE and the chromosome 12 locus might have independent effects. We have since genotyped several additional markers across the region, to refine the linkage results. In analyzing these additional data, we have addressed the issue of heterogeneity in the data set by weighting results by clinical and neuropathologic features, sibship size, and APOE genotype. When considering all possible affected sib pairs (ASPs) per nuclear family, we obtained a peak maximum LOD score between D12S1057 and D12S1042. The magnitude and location of the maximum LOD score changed when different weighting schemes were used to control for the number of ASPs contributed by each nuclear family. Using the affected-relative-pair method implemented in GENEHUNTER-PLUS, we obtained a maximum LOD score between D12S398 and D12S1632, 25 cM from the original maximum LOD score. These results indicate that family size influences the location estimate for the chromosome 12 AD gene. The results of conditional linkage analysis by use of GENEHUNTER-PLUS indicated that evidence for linkage to chromosome 12 was stronger in families with affected individuals lacking an APOE-4 allele; much of this evidence came from families with affected individuals with neuropathologic diagnosis of dementia with Lewy bodies (DLB). Taken together, these results indicate that the chromosome 12 locus acts independently of APOE to increase the risk of late-onset familial AD and that it may be associated with the DLB variant of AD.

Cholinesterase inhibitors for the treatment of Alzheimer's disease in the elderly

The treatment of Alzheimer's disease is of increasing importance as the population ages and the number of people with the disease increases. The aetiology of Alzheimer's disease is complex and therefore treatment strategies rely on generalised pathological findings. Cholinesterase inhibitors enhance a generalised deficit of central nervous system acetylcholine and are the first class of agents specifically approved for the treatment of Alzheimer's disease. The clinical efficacy of the different cholinesterase inhibitors is similar; however, differences in pharmacodynamic and pharmacokinetic parameters can influence tolerability and safety in the elderly population. Concomitant disease states, significant drug interactions and the altered kinetics and dynamics seen in elderly patients can also affect treatment outcome. Although cholinesterase inhibitors are not 'curative' for Alzheimer's disease, clinical evidence indicates that these drugs can significantly delay the progress of cognitive impairment. Consequently, they represent a useful treatment for the symptoms of Alzheimer's disease in the elderly.

Attenuation of neurodegeneration-relevant modifications of brain proteins by dietary soy

Epidemiological studies show that postmenopausal women who undertake estrogen-replacement therapy have significantly lower risk for the onset of Alzheimer's disease (AD) than women who do not. Animal behavior studies have shown that ovariectomy results in the development of cognitive dysfunction that is prevented by estrogen-replacement, suggesting that normal mammalian cognitive function is impaired by estrogen reduction. Soy isoflavones in particular genistein have been demonstrated to have weak and selective estrogenic actions in various models of human chronic diseases. A hallmark of several human dementias including AD and fronto temporal dementia with Parkinsonism on chromosome 17 (FTDP-17) is the hyperphosphorylation of the microtubule-associated protein tau. Preliminary experiments are discussed here which show that isoflavones delivered in a soy protein matrix attenuated selected AD-relevant tau phosphorylations in a primate model of menopause. The rationale is discussed for the use of soy-based foods for protection against postmenopausal neurodegeneration.

Morphologic alteration of the olfactory bulb after acute ozone exposure in rats

The interaction of ozone with some molecules results in an increased production of free radicals. The objective of this study was to identify whether acute ozone exposure to 1-1.5 ppm for 4 h, produced cytological and ultrastructural modifications in the olfactory bulb cells. The results showed that in rats exposed to ozone there was a significant loss of dendritic spines on primary and secondary dendrites of granule cells, whereas the control rats did not present such changes. Besides these exposed cells showed vacuolation of neuronal cytoplasm, swelling of Golgi apparatus and mitochondrion, dilation cisterns of the rough endoplasmic reticulum. These findings suggest that oxidative stress produced by ozone induces alterations in the granule layer of the olfactory bulb, which may be related to functional modifications.