Identifying patterns in signs and symptoms preceding the clinical diagnosis of Alzheimer’s disease

Previous research indicates that there is a major challenge caused by the late diagnosis of Alzheimer's disease (AD), with no suitable diagnostic tool available for use in primary care. Aim: This research is aimed at identifying patterns in the early signs and symptoms of AD to suggest the development of a predictive model for the early detection of AD. Objectives: To; a) map, synthesise and appraise the quality of existing literature on the signs and symptoms preceding the diagnosis of AD via the systematic scoping review of the literature; b) identify patterns in signs and symptoms preceding the clinical diagnosis of AD in general practices via a retrospective medical record review study (RMRRS); c) explore the clinicians perspectives regarding the early signs and symptoms, issues surrounding the late diagnosis and collect recommendations for overcoming barriers to timely detection of AD via a semi-structured interview. Methods: This was a mixed method research comprising a systematic scoping review of literature from 1937-2016, undertaken using the descriptive analysis on the sequence and the timing of signs and symptoms preceding the diagnosis of AD. Methodological quality of studies was assessed with the QUADAS-2 tool as well as PRISMA guidelines and descriptive analysis followed. A RMRRS followed using the logistic regression analysis and a semi-structured interview of general practitioners (GPs) in Milton Keynes (MK) and Luton, using the framework analysis. Results: The findings from the review suggest that neurological and depressive behaviours are an early occurrence in early-onset AD with depressive and cognitive symptoms in the measure of semantic memory and conceptual formation in late-onset AD. It appears that there is a big variation in the patterns of signs and symptoms with cases of misdiagnosis. However, there was limited evidence due to the limited number of studies of this kind. The nested case control design of 109 samples indicates that auditory disturbances could have diagnostic value, with a range of signs and symptoms that appears at different time. While the interviews highlight and confirm areas for consideration in the primary care and NHS. Additionally, the study reports practices in relation to the early diagnosis of AD. However, the result is not an overall representation of the views of GPs. Conclusion: Findings suggest that individuals with auditory disturbances have increased odds of AD. This was more striking in the white female population, with borderline significance due to limited data that is too small to detect such an uncommon symptom(s).