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Article abstract-Clinical and neuropathologic evidence points to the development of Alzheimer's disease (AD) in seven Down's syndrome patients above age 40. Dementia was observed in these patients over periods of 2.5 to 9.2 years. The first clinical sign of AD, visual memory loss, was succeeded by impaired learning capacity and decreased occupational and social functioning, and culminated in seizures and urinary incontinence. The morphometric observations of the brains of these seven patients with AD showed that the numbers of plaques and tangles exceeded 20 per 1.5 X 10" pm2 area, in both the prefrontal and hippocampal cortices. Plaques and tangles were also evident in the basal ganglia, thalamus, hypothalamus, and midbrain. In addition, we found that four of the seven brains showed small strokes, and five of the seven amyloid angiopathy. This study also indicates that by longitudinal neuropsychological evaluations and lab tests, which exclude other causes of dementia, the diagnosis of AD can be made even in severely and profoundly retarded patients. NEUROLOGY 1985;35:957-961 Alzheimer's disease in Down's syndrome:Clinicopathologic studies Clinical documentation of AD in DS patients has been made largely by retrospective studies. Moreover, the patients studied who were often institutionalized with profound mental retardation, provided conflicting information in that estimates of AD changes varied from 15%H to 27%" "'to 100%." In a prospective study'j covering 10 years, clinical evidence of AD was seen in 12 of 49 DS patients above age 40 years (24%).We now provide a clinicopathologic description of seven patients with DS with documented clinical manifestations of Alzheimer's dementia extending from 2.5 to 9.2 years before death. Materials and methods. Clinical methods. Cognitivefunctions, defined as learning capacities and memory functions, were assessed quantitatively on a repeated, follow-up basis for five of the seven patients, using methods developed previously.' I I h To minimize the effects of environmental (test) conditions, each patient was examined with the same test materials under conditions as nearly identical as possible in a specially equipped mobile laboratory. T o rule out causes of memory and learning incapacities unrelated to Alzheimer's disease, control studies were performed with different patients and examiners.'4,'A Neurologic examination for focal and frontal release signs were conducted by D.R. Crapper McLachlan. Other clinical data used to estimate "overall regression" were obtained from personal reports by staff and from medical records. Neurologic examinations were conducted on an irregular basis two or three times before death. Cognitive assessments were conducted between two and six times, a t approximately lllr-year intervals.Criteria for inclusion in the study (excluding patient 5) were normal birth record, no prior recorded history of seizures, no gross sensory or motor impairment, and no evidence of focal neurologic signs.Gross and microscopic neuropathologic methods. Each br...

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We investigated a possible relation between aluminum concentration ([Al]) in public drinking water and Alzheimer's disease (AD), with AD cases and controls defined on the basis of strict neuropathologic criteria. Using the case/control odds ratio as an estimate of relative risk and [Al] > or = 100 microgram/L as the cutoff point, elevated risks for histopathologically verified AD were associated with higher [Al]. Comparing all AD cases with all non-AD controls, and using the [Al] of public drinking water at last residence before death as the measure of exposure, the estimated relative risk associated with [Al] > or = 100 microgram/L was 1.7 (95% CI: 1.2-2.5). Estimating aluminum exposure from a 10-year weighted residential history resulted in estimates of relative risk of 2.5 or greater. The public health implications of the observed relationship between [Al] in drinking water and AD prevalence in the population depend in large measure on population exposure characteristics. In Ontario, it is estimated that 19% of the population was exposed to residual [Al] greater than or equal to 100 microgram/L. Based on the estimated relative risk and the assumption of causality, this translates to an etiologic fraction of 0.23. Although the potential contributions of confounding and mitigating factors are not defined in this report, the merit of limiting residual aluminum in drinking water supplies deserves serious attention.

SUMMARYThe strength of the evidence implicating aluminium as an important factor in the dementia of Alzheimer's disease (AD) is reviewed. We submit that the weight of the epidemiological and biological arguments is considerable. While a complete understanding has not been achieved, we recommend lowering aluminium exposure in municipal drinking water to below 50 pg/l in at least the province of Ontario. The Ministry of Energy and the Environment of Ontario maintains a drinking water surveillance programme which has provided a database for more than 10 years. This database has permitted assessment of the relative risk for AD using four independent measures of disease prevalence: 1. weighted residential history as a measure of exposure in autopsy-verified AD cases and controls; 2. first admission hospital discharge diagnoses of AD and controls; 3. death certificate rates for AD and presenile dementia; 4. impairments in cognitive function in elderly males. Taken together, many of the criticisms applied to epidemiological studies conducted elsewhere and reaching similar conclusions have been met. A vast experimental database on aluminium neurotoxicity, rapid advances in the understanding of the molecular basis of AD, and comparison studies between human brains exposed to chronic low dose aluminium exposure secondary to renal failure and AD, lend strong biological support to the conclusions reached by the epidemiological studies. The factors initiating AD, how aluminium gains access to the brain in AD, and the relative contributions of food, pharmaceuticals and skin absorption, remain unknown. While a full understanding is not in hand, the devastating nature of the disease, the lack of an effective treatment or prevention and the high cost to the health care system, together with the human costs, weighed against the relative cost of moderately reducing drinking water aluminium concentration to reduce exposure indicate that action is both reasonable and timely. KEY WORDSAlzheimer's disease; aluminium ALZHEIMER'S DISEASE: THE PROBLEMAlzheimer's disease (AD) is a slowly progressive, lethal, brain disorder which affects memory and other cognitive functions. AD is the most common cause of senile dementia and the prevalence in the age group over 65 years has been estimated to range between 9 per cent' and 5-5 per cent.2 The onset of AD is uncommon under the age of 65 (presenile dementia), but no less tragic. About 10 per cent of all cases occur in families (known as familial Alzheimer's disease (FAD)) and are inherited as an autosomal dominant disorder.The AD degenerative process renders victims mentally incompetent with progressive loss of self-help skills. The prolonged clinical course of the disease over ten or more years results in a particularly heavy burden of care upon the next-of-kin, the community social support systems, and, eventially, chronic care institutions, where the terminal phase may last three or more years. The brain changes which distinguish AD from all other causes of senile dementia are loss of neurons...