Dementia and age at death

Understanding Aspects of Aluminum Exposure in Alzheimer's Disease Development

Aluminum is a ubiquitously abundant nonessential element. Aluminum has been associated with neurodegenerative diseases such as Alzheimer's disease (AD), amyotrophic lateral sclerosis, and dialysis encephalopathy. Many continue to regard aluminum as controversial although increasing evidence supports the implications of aluminum in the pathogenesis of AD. Aluminum causes the accumulation of tau protein and Aβ protein in the brain of experimental animals. Aluminum induces neuronal apoptosis in vivo and in vitro, either by endoplasmic stress from the unfolded protein response, by mitochondrial dysfunction, or a combination of them. Some, people who are exposed chronically to aluminum, either from through water and/or food, have not shown any AD pathology, apparently because their gastrointestinal barrier is more effective. This article is written keeping in mind mechanisms of action of aluminum neurotoxicity with respect to AD.

Cause of death in Alzheimer's disease: a cohort study

BACKGROUND

Reporting of cause of death in patients with Alzheimer's disease (AD) has changed over the past few decades but concerns persist over the accuracy of death certificate completion in this setting.

OBJECTIVES

To examine the causes of death in AD and examine how this compares with those affecting the normal population.

METHODS

Death certificates were obtained for 85 AD patients and 52 control subjects from a cohort of 396 participants. Underlying causes of death and other conditions mentioned on the death certificates of the AD patients were analysed and compared with the Northern Ireland population age-and-sex adjusted mortality rates and subsequently to the death certificates of control subjects.

RESULTS

AD and pneumonia were causes of significant excess mortality and the most common underlying causes of death in the AD patient group (23.53 and 17.65%, respectively). When compared with the control subjects, AD and gastrointestinal diseases were found to be more prevalent. AD was recorded on 63.5% of death certificates of AD subjects who died during follow-up.

CONCLUSION

The cause of death documented for AD patients may be affected by the physician's knowledge of the patient or reflects the approach to management of patients with end-stage dementia.

Dementia time to death: a systematic literature review on survival time and years of life lost in people with dementia

BACKGROUND

Life expectancy with dementia directly influences rates of prevalence and service needs and is a common question posed by families and patients. As well as years of survival, it is useful to consider years of life lost after a diagnosis of dementia.

METHODS

We systematically reviewed the literature on mortality and survival with dementia which were compared to estimated life expectancies in the general population. Both were then compared by age (under 65 years vs. 65+ years), gender, dementia type, severity, and two epochs (prior to and after introduction of cholinesterase inhibitors in 1997).

RESULTS

Survival after a diagnosis of dementia varies considerably and depends on numerous factors and their complex interaction. Relative loss of life expectancy decreases with age at diagnosis across varying gender, dementia subtypes (except for frontotemporal dementia and dementia with Lewy bodies), and severity stages. Numerous study deficiencies precluded a meta-analysis of survival in dementia.

CONCLUSION

Estimates of years of life lost through dementia may be helpful for patients and their families. Recommendations for future research methods are proposed.

Death and dementia

OBJECTIVE

To investigate the last phase of dementia and the causes of death; comparing autopsy and death certificate diagnoses.

DESIGN

Prospective, 11-year, longitudinal study of behavioural and psychological changes in dementia, with autopsy follow-up.

SETTING

Participants with dementia, living at home with a carer. All lived in Oxfordshire, UK.

PARTICIPANTS

Ninety-one people with dementia (Alzheimer's disease and/or vascular dementia) who died during the course of the study.

MEASURES

At four-monthly intervals, carers were interviewed about the participants' behaviour using the Present Behavioural Examination. Participants were also assessed cognitively. Causes of death were established from death certificates and, where possible, from post-mortem examination.

RESULTS

The main immediate cause of death recorded at autopsy was pneumonia (57%), followed by cardiovascular disease (16%) and pulmonary embolus (14%). This agreed with the immediate cause of death on 53% of death certificates. Pulmonary embolism and bronchopneumonia were under-reported on death certificates. Dementia was mentioned on 73% of death certificates. The dementing illness lasted for a mean of 8.5 years with 58% dying in a debilitated state associated with severe dementia. In the period before death, 35% were unable to walk, 58% were hypophagic, 73% were incontinent of urine, 21% incontinent of faeces and 76% entered an institution permanently for a mean period of 18 months.

CONCLUSION

Family and professional carers of people with dementia can be given some information about prognosis to help them plan for the likely outcome of dementia.

Dementia is a major predictor of death among the Italian elderly. ILSA Working Group. Italian Longitudinal Study on Aging

BACKGROUND

Neurologic diseases are rarely listed on death certificates because death is more often attributed to cardiovascular and pneumonic events occurring during terminal stages.

OBJECTIVE

To evaluate the effect of major age-associated neurologic and non-neurologic diseases on survival in a cohort of Italian elderly.

METHODS

A population-based multicenter survey, carried out in eight Italian municipalities, with a sample of 5,632 individuals aged 65 to 84 years. The entire sample was screened for all the diseases under study, and all individuals were interviewed about risk factors. Those who screened positive underwent clinical assessments by specialists. Two years after the baseline survey, the study population was followed up to determine the vital status either directly from the individuals or from proxy respondents. A copy of the death certificate was obtained for each individual who had died. The risk of dying (mortality risk ratio [MRR]) was calculated using the Cox proportional hazards model in which we included all the diseases under study, age, gender, and years of education.

RESULTS

At follow-up (mean duration 26.7 +/- 5.4 months) 444 individuals had died. The Cox proportional hazards model selected the following as significant predictors of death: age (for year of age MRR = 1.12; 95% confidence interval [CI], 1.08 to 1.15), male gender (MRR = 1.72; 95% CI, 1.27 to 2.34), institutionalization (MRR = 4.17; 95% CI, 2.20 to 7.94), dementia (MRR = 3.61; 95% CI, 2.55 to 5.11), neoplasm (MRR = 2.01; 95% CI, 1.20 to 3.38), heart failure (MRR = 1.87; 95% CI, 1.27 to 2.76), and diabetes (MRR = 1.62; 95% CI, 1.12 to 2.34).

CONCLUSIONS

These data provide further evidence on the malignancy of dementia, which proved the major predictor of death in the elderly, with an MRR higher than neoplastic diseases and other severe age-associated conditions.

Comparison of risk estimates for selected diseases and causes of death

BACKGROUND

Lifetime risk estimates of disease are limited by long-term data extrapolations and are less relevant to individuals who have already lived a period of time without the disease, but are approaching the age at which the disease risk becomes common. In contrast, short-term age-conditional risk estimates, such as the risk of developing a disease in the next 10 years among those alive and free of the disease at a given age, are less restricted by long-term extrapolation of current rates and can present patients with risk information tailored to their age. This study focuses on short-term age-conditional risk estimates for a broad set of important chronic diseases and nondisease causes of death among white and black men and women.

METHODS

The Feuer et al. (1993, Journal of the National Cancer Institute) [15] method was applied to data from a variety of sources to obtain risk estimates for select cancers, myocardial infarction, diabetes mellitus, multiple sclerosis, Alzheimer's, and death from motor vehicle accidents, homicide or legal intervention, and suicide.

RESULTS

Acute deaths from suicide, homicide or legal intervention, and fatal motor vehicle accidents dominate the risk picture for persons in their 20s, with only diabetes mellitus and end-stage renal disease therapy (for blacks only) having similar levels of risk in this age range. Late in life, cancer, acute myocardial infarction, Alzheimer's, and stroke become most common. The chronic diseases affecting the population later in life present the most likely diseases someone will face. Several interesting differences in disease and death risks were derived and reported among age-specific race and gender subgroups of the population.

CONCLUSION

Presentation of risk estimates for a broad set of chronic diseases and nondisease causes of death within short-term age ranges among population subgroups provides tailored information that may lead to better educated prevention, screening, and control behaviors and more efficient allocation of health resources.

Further thoughts on the aluminum-Alzheimer's disease link

STUDY OBJECTIVE AND METHOD: The results of studies on aluminum (Al) and Alzheimer's disease (AD) from groups in Newcastle, UK and Ontario, Canada were compared in order to explain why the former were unable to detect a link while the latter could, and to suggest alternative ways of examining the data.

RESULTS

The Al concentrations in the Newcastle study were relatively small compared with the Ontario ones. When Al concentrations > 250 micrograms/l were used, the RRs were greater for AD than for other forms of dementia, and the RRs were lower for those under 75 years and greater at ages 85 years and over than at ages above 75 years. The relationship between dementia and Al concentrations was U or J shaped--there was a minimum at an Al concentration of 100 micrograms/l. Other constituents or properties such as silicic acid, fluoride, turbidity, iron, and pH all have an effect on the relationship.

CONCLUSIONS

Analyses of the type reported from Newcastle can yield further information if they are extended to include multivariate analyses that take account of other water constituents which can affect the relationship between Al water concentrations and AD are carried out. The relationship between Al and dementia may be U or J shaped rather than linear. With regard to AD, the group aged less than 65 years is not the best one in which to explore a relationship. Lastly, it may be that a link with AD is most meaningful at relatively high Al water concentrations.