Alzheimer's disease currently affects over 800,000 people in the UK, and this figure is set to exceed 1.5 million by 2050. The disease causes a severe breakdown of the brain, resulting in the progressive decline in the mental health of the patient. It also remains without a long-term cure. A definitive diagnosis of the disease can only be gained at post-mortem, whilst other technologies are limited to monitoring the physical breakdown of the brain. The early identification of the chemicals responsible for the disease, and their structure, is therefore essential for improved diagnosis, treatment and care. This research demonstrates the use of Raman spectroscopy, and principle components analysis, as a method for the diagnosis, and examination of, the specific proteins responsible for Alzheimer's disease. Analyses of ethically approved ex vivo brain tissues from normal elderly (n=3), Alzheimer's disease (n=12) and Huntingdon's disease (n=3) brain sections (from the frontal and occipital lobes) are presented. Subsequently, a further 12 blinded individual samples were examined and the preliminary results are presented. Spectra originating from these tissues are highly reproducible, and results indicate a vital difference in protein content and protein conformation, relating to the abnormally high levels of aggregated proteins in the diseased tissues. Principle components analysis has been shown to differentiate normal elderly tissues from diseased tissues. These results show great promise for the early identification of Alzheimer's disease, and secondary information regarding other brain diseases and dementias. These results demonstrate the potential use of Raman spectroscopy as a possible non-invasive, non-destructive tool for the early diagnosis of Alzheimer's disease.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.