A re-analysis of the data from 11 case-control studies was performed to investigate the association between head trauma and Alzheimer's disease (AD). To increase comparability of studies, exposures were limited to head trauma with loss of consciousness (hereafter referred to as 'head trauma') and comparisons were restricted to community (versus hospital) controls. Test for heterogeneity across studies was negative; consequently, data were pooled in subsequent analyses. The pooled relative risk for head trauma was 1.82 (95% confidence interval: 1.26-2.67). Stratified analyses showed stronger associations in cases without a positive family history of dementia and in males (versus females). Adjustment of the pooled relative risk for family history of dementia, education and alcohol consumption did not alter significantly the association between head trauma and AD. There was no interaction effect between head trauma and family history of dementia, suggesting that these risk factors operate independently. Mean age of onset was not significantly different in cases with a history of head trauma compared to cases without such a history. The findings of the pooled analysis support an association between reported head trauma and AD.

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In a re-analysis of eight case-control studies on Alzheimer's disease we explored several medical conditions that had previously been suggested as possible risk factors for Alzheimer's disease. History of hypothyroidism was increased in cases as compared to controls (relative risk 2.3; 95% confidence interval 1.0-5.4). Severe headaches and migraine were inversely related to Alzheimer's disease (relative risk 0.7; 95% confidence interval 0.5-1.0). More cases than controls reported epilepsy before onset of Alzheimer's disease (relative risk 1.6; 95% confidence interval 0.7-3.5), especially for epilepsy with an onset within 10 years of onset of dementia. Neurotropic viruses, allergic conditions, general anaesthesia and blood transfusions were not associated with Alzheimer's disease.

A meta-analysis, involving the secondary analysis of original data from 11 case-control studies of Alzheimer's disease, is presented for occupational exposures to solvents and lead. Three studies had data on occupational exposure to solvents. Among cases, 21.3% were reported to have been exposed; among controls, this figure was comparable (20.9%). This yielded a pooled matched relative risk of 0.76 (95% CI: 0.47-1.23). Four studies had data on exposure to lead. Exposure frequencies were 6.1% in cases and 8.3% in controls. This resulted in a pooled matched relative risk of 0.71 (95% CI: 0.36-1.41). The meta-analysis was particularly useful in validating negative results from individual studies and in increasing the statistical power for the analysis of lead exposure, where stratum-specific cell sizes were frequently smaller than five in individual studies. However, since exposure in the various studies was ascertained in a rather broad manner, prospective studies are recommended which focus on high-risk occupational populations and which determine the incidence of Alzheimer's disease in these and comparable unexposed populations.

SUMMARYA retrospective chart review was completed on the 122 cases of CDAD for the period of 1965-1970 identified from a longitudinal study of dementia a t the Mayo Clinic. A psychiatrist assigned DSM-111-R diagnoses based upon the longitudinal description of symptoms detailed in the medical records of the Mayo Clinic hospitals, nursing home visit records and state hospital records.Thirty patients (25%) were found to have an episode of delirium (EOD) during their course of CDAD which occurred during inpatient admissions. Single EODs were found to occur within 2 years of the onset of CDAD, and multiple EODs within 3 years of the onset of CDAD. A psychiatric consultation was requested in only 14% of the sample ( N = 17); 88% of these patients received diagnoses involving primary degenerative dementia of the Alzheimer's type, late onset. Psychopharmacology was the major management strategy (82Y~ of patients with an EOD received medication) with the resolution of symptoms within 48 hours. At discharge, only two patients (7%)) failed to completely clear the increased degree of confusion. Implications of these findings for the management of patients with CDAD and the management of EOD with the knowledge of the 1990s are discussed.KEY WORDS-Delirium, dementia, management. Delirium is an acute confusional state characterized by a global disturbance in cognitive function. Thinking, perception and awareness are all impaired (Blass et al., 1991). The causes of delirium are protean and include metabolic derangement due to electrolyte imbalance or hepatorenal failure,