The Epidemiology of Presenile Alzheimer's Disease in Scotland (1974-1988): Diagnosis, Incidence Rate and Natural History

McGonigal, Gerard (1993) The Epidemiology of Presenile Alzheimer's Disease in Scotland (1974-1988): Diagnosis, Incidence Rate and Natural History. MD thesis, University of Glasgow.

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Objectives - To evaluate clinical criteria to diagnose Alzheimer's disease and to describe the epidemiology of presenile Alzheimer's disease in Scotland from 1974 to 1988. Design - Retrospective review of hospital records of patients aged less than 73 years admitted to psychiatric hospital with various diagnoses of dementia. Diagnoses were classified by National institute of Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association Criteria (NiNCDS- ADRDA) and the Hachinski score. Accuracy of diagnosis was assessed by reference to the neuropathological diagnosis in those who underwent postmortem examination. Completeness of the study sample was evaluated by scrutiny of selected neurology outpatient and general hospital records. Setting - All general psychiatric hospitals in Scotland. Subjects - All patients with onset of dementia aged 40-64 years inclusive. Main outcome measures - Probable, broad and definite Alzheimer's disease, sex of patient, age at onset, age at presentation, date of death, place of death. Results - 5874 psychiatric hospital records, 129 neurology outpatient records, 89 records from non-psychiatric hospitals and 61 neuropathology records were examined. A discriminant function analysis, which entered the clinical criteria as variables, was performed and the diagnostic accuracy of the clinical criteria was compared before and after the analysis. NINCDS-ADRDA criteria had a diagnostic accuracy of 72% (specificity 88%, sensitivity 61%) compared to 77% (specificity 80%, sensitivity 75%) after analysis. NINCDS-ADRDA criteria together with a Hachinski score had an accuracy of 72% (specificity 61%, sensitivity 88%) compared to 83.6% (specificity 76%, sensitivity 89%) after analysis. Variables of highest discriminating value were the Hachinski score, presence of coexistent neurological disease and presence of coexistent systemic disease. 317 patients met criteria for probable Alzheimer's disease and 569 met criteria for broad Alzheimer's disease. Minimal incidences per 100 000 population aged 60-64 years were 22.6 (95% confidence interval, 20.2 to 25.2) and 40.5 (38.9 to 42.3) per 100 000 for probable and broad Alzheimer's disease. In the 1981 census year the annual incidence of probable Alzheimer's disease was 1.6 (1.0 to 2.6). Female gender was associated with a higher incidence of probable and broad Alzheimer's disease. The live year survival rate for probable Alzheimer's disease was 51.2% decreasing to 17.3% at ten years. Females survived 1.3 times longer than males (95% confidence interval 1.04 to 1.61). Place of death, age at presentation and year of presentation did not significantly affect survival duration. There was no evidence of increased survival in those patients with probable Alzheimer's disease over the time period from 1974 to 1988. Conclusions - Current clinical criteria used to diagnose Alzheimer's disease are limited and can be substantially improved. Female gender is positively associated with the development of Alzheimer's disease before age 65 years. Female patients with a clinical diagnosis of probable Alzheimer's disease live longer than male patients with the same diagnosis.

Item Type: Thesis (MD)
Qualification Level: Doctoral
Additional Information: Adviser: Lawrence J Whalley
Keywords: Epidemiology, Cognitive psychology, Neurosciences
Date of Award: 1993
Depositing User: Enlighten Team
Unique ID: glathesis:1993-74800
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 13 Nov 2019 15:58
Last Modified: 13 Nov 2019 15:58

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