Risk factors, causality, and policy initiatives: the case of aluminum and mental impairment.

The question addressed is when can the evidence concerning a health issue be regarded as adequate to implement policy initiatives. The approach is illustrated by comparing evidence about the effects of cigarette smoking with evidence for the aluminum (Al) hypothesis (that Al contributes to mental impairment and especially to Alzheimer's Disease). The criteria for evaluating the evidence are based on the consistency and strength of the association between a putative risk factor and the relevant outcome variable, the likelihood that the relative risk represents a causal relationship, whether possible mechanisms are available, the number of persons affected, and the costs of modifying the risk factor.

Dementia and age at death.

The objective of this paper is to investigate changes in dementia mortality, as recorded on death certificates in Canada. Use is made of data available at Statistics Canada for the period 1990-1991. During this period there have been appreciable changes over time in the ages at death and in the percentage of death certificates that mention dementia. This increase in mortality associated with dementia can be explained, in large part, by an increased tendency for dementia to be listed as an underlying cause of death on the death certificate. Also, the median ages at death of persons in Canada for the period 1990-1991, for whom dementia is recorded as the underlying cause of death, are similar to or greater than the ages at death reported for all other causes of death but excluding dementia. Because those who have dementia are living longer, there is an increase in the number of people with dementia (prevalence of dementia); this has important implications concerning public policy on health and aging. We discuss the significance of these changes with respect to the future prevalence of dementia.

Concerning the role of aluminum in causing dementia.

Topics outlined in an earlier paper by Eichhorn are expanded, with particular emphasis on the implications of the associations between aluminum (Al) concentrations and various indications of mental impairment. These associations represent the main thrust of the evidence that Al is a contributory cause for some forms of dementia. Of particular interest are the more recently observed associations between Al concentrations in drinking (finished) water and various indications of mental impairment, and the relevance of other water quality variables such as silica, fluoride, and pH. Various unresolved questions are also identified.

The importance of social relationships, socioeconomic status and health practices with respect to mortality among healthy Ontario males.

The associations of social relationships, socioeconomic status and health practices with 20-year mortality were examined in a cohort of 2000 Ontario males. A social relationships index comprised of marital status, number of children, family contact and participation in voluntary associations had a strong association with mortality (adjusted relative risk of 0.30, 95% CI 0.11-0.83, comparing the highest 10% with the lowest 10% scores of the index). Among indicators of socioeconomic status, only income was significantly related to mortality with an adjusted relative risk of 0.41 (95% CI 0.23-0.72) for the highest 20% compared with the lowest 20% income group. The adjusted relative risk for smokers compared with non-smokers was 2.26 (95% CI 1.51-3.37). The joint effects of a relatively high score in the social relationships index, high income and being a non-smoker is estimated to represent an approximately 18-fold reduction in the risk of mortality during the follow-up period.

The relationship between aging and disease: geriatric ideology and myths of senility.

An ongoing debate in gerontology concerns the relationship between aging and disease. Goodwin, as part of a discussion on the importance of geriatric ideology, argues that age-related disorders like senile dementia of the Alzheimer's type (SDAT) should be regarded as an aging process, while others suggest it is more appropriate to consider it as a disease. This paper comments on the arguments presented by Goodwin and develops these by providing a review of the underlying assumptions concerning aging and disease. The policy relevance and implications for future research are also outlined.

Autopsy data and their total evaluation.

The role of the autopsy is discussed in the study of the etiology of the current major causes of death (cardiovascular and neoplastic diseases) in developed countries. Evidence is accumulating for the importance of environmental factors in the etiology of these diseases. The study of regional differences in occurrence is described as a method of identifying specific factors. Maps are shown of mortality rates for all causes of death in Ontario counties for males aged 65-74 and 95+ during 1964-68. Some of the difficulties in obtaining data in this form, and in their analysis, are indicated. Regional mortality patterns can be interpreted by the use of associations with available regional socioeconomic measures, or by the use of regional data on trace-metal levels in autopsy samples of human lung, rib, vertebra, kidney and liver. The methodology and the difficulties involved in the determination of trace-metal levels in these tissues are discussed, as is the possible relevance of these levels to the study of degenerative diseases. All these considerations emphasize the valuable contributions of autopsy studies.

Further thoughts on the aluminum-Alzheimer's disease link.

UNLABELLED: 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.

Reasons for the disagreements on the impact of smoking on medical care expenditures: a proposal for a uniform approach.

A recent paper suggested that smoking does not increase medical care expenditures and, therefore, that reduced smoking is unlikely to decrease it. This conclusion differs from that of most other studies in this area and the reasons for this disagreement are investigated. It is pointed out that medical care expenditure estimates yield different results depending on whether they are estimated on a per capita basis or in total for populations which change in size as smoking is reduced or eliminated. To avoid disagreement in future studies of this type, some specific proposals are made which should facilitate the comparison of results obtained from different studies.

Smoking and its effect on mortality of the elderly.

The effects of smoking on the mortality experience of elderly populations are considered by comparing the mortality rates for elderly smokers, ex-smokers and nonsmokers. This question arose since a recent study, using similar data, suggested that there was no health benefit for elderly cigarette smokers who discontinue cigarette smoking. Although ultimately in the latter part of the life-span, the benefit which might be gained by giving up smoking would not increase life-span significantly, the present study shows that for all of the older age groups investigated, a lower mortality from all causes of death is observed for nonsmokers and ex-smokers compared with elderly smokers. Consequently, even though no direct evidence is available, from this or other studies, as to whether it is desirable for elderly smokers to discontinue smoking, because of the general consistency of the data for the younger and older age groups, it seems probable that giving up smoking represents a health benefit for most older smokers.

Concerning the prevalence of dementia.

A recent paper asserted that despite difficulties of measurement, the evidence suggests that the prevalence of dementia may be lower than is generally realized. However, this paper neglected the information provided by other recent studies which show relatively high values for the prevalence of dementia. On the basis of these latter studies and considering non-response, it is here suggested that, in fact, there is no good reason to suspect that the prevalence of dementia is lower than is generally believed.

Aspects of preventive health care for older persons.

Preventive health care for older persons is considered in terms of primary, secondary and tertiary prevention and examples of relevant services are provided both from Canada and from other countries. Three areas of concern are identified, namely communication, quality assurance and funding. It is suggested that various approaches used in other countries, such as Home Visitor Programs, be examined and more generally that comparisons with health care services in other countries be carried out, particularly with respect to evaluations and possible economic steering effects.

The quantitative evaluation of risks: unresolved problems.

Various generators of risk which are believed to be important, namely unhealthy diet, hazardous occupations, smoking, poverty, radiation and chance of war are considered. The considerations which are relevant for policy in risk evaluation are taken to be the magnitude of the risk, the strength of the evidence that the risk is real, the size of the population at risk and the ease of modification of a behaviour involving risk. Various measures for judging risk are outlined, including mortality rates, relative mortality rates, morbidity measures, and more extensively the analysis of "costs and benefits". The importance of longitudinal studies is stressed. A theoretical framework is presented to describe formally how risk can be quantified. This is followed by a discussion of risks associated with specific hazardous activities. It is suggested that among those considered, poverty and nuclear war represent the greatest risks, followed by smoking and, in decreasing order of priority, industrial risks and poor diet.

Aluminum, fluoride and the prevention of Alzheimer's disease.

The evidence regarding the link between aluminum and Alzheimer's disease is summarized. This evidence suggests strongly that aluminum is one of the etiologic or contributing factors in the occurrence of Alzheimer's disease. One reported study suggests that relatively high fluoride in drinking water plays a preventive role in Alzheimer's disease. The rationale for this is the evidence that aluminum and fluoride compete for absorption in the gut. However, this study had methodologic limitations, and no firm conclusion can be drawn. Further investigation of relatively high fluoride in drinking water as a preventive measure for Alzheimer's disease should receive high priority.

Factors associated with the prevalence of various self-reported impairments among older people residing in the community.

Self-reported data from the Health and Activity Limitation Survey (HALS) and the General Social Survey (GSS) are used to estimate the prevalence of psychological or mental, mobility, agility, seeing and hearing impairments in the elderly population. Multiple impairments are common in the elderly population and the prevalence of the various impairments increases with age in a log-linear manner. Relative risks are estimated for the various impairments on the basis of income, marital status, housing tenure and living arrangements. Among these four variables, low income appears to have the greatest effect.

Factors associated with self-reported use and non-use of assistive devices among impaired elderly residing in the community.

We report an analysis of data from the Health and Activity Limitation Survey (HALS) pertaining to the use of assistive devices. The focus is on elderly people reporting an impairment who did not use assistive devices. The degree of impairment, type of impairment, and socio-demographic variables were analyzed for their association with non-use of assistive devices. The non-use of assistive devices was often found to be consistently and strongly correlated for women who report social isolation, less education and who reside in rural areas, suggesting that these groups could be the target for policy initiatives.

The role of carbon monoxide in cigarette smoking. I. Carbon monoxide yield from cigarettes.

The carbon monoxide deliveries of 20 major Canadian brands of cigarettes, determined by gas chromatography and using standard smoking conditions, were estimated and found to vary by a factor of about two. The CO yields were found to increase with puff volume and tobacco moisture, decrease with increased paper porosity, but remain essentially constant with puff duration. The data suggest that reduced CO deliveries can be achieved by increasing the cigarette paper porosity. Combustion temperature presumably also influences CO deliveries, but the relative role ascribed to dilution and combustion is not clear. It may be concluded that smokers can lower their CO exposure by reducing their puff volume, smoking cigarettes manufactured from high porosity paper, by taking fewer puffs, and decreasing their tendency to inhale. Since CO and tar deliveries are correlated, these measures would also tend to decrease a smoker's exposure to tar.