Alzheimer’s disease diagnosis is mainly based in the identification of the cognitive disorder in patients who have already overt the advanced stage of dementia, when is too late for some kind of therapeutic adjustment. Therefore, in order to improve early recognition of Alzheimer’s disease, novel approaches for biomarkers identification, such as metabolomics, are been developed and the potential of Fourier Transform Infrared Spectroscopy (FTIR) in the clinical field is receiving particular attention.

The present work aims to contribute to identification of the main pathological changes that occurred during neurodegeneration, by identifying plasma biochemical alterations that might be related to dementia and discriminate control from cognitive impaired samples, through FTIR analysis. Multivariate analysis was applied to spectra data (n=45). Plasma samples from cognitive impaired subjects presented a higher content of saturated lipids in relation to the unsaturated ones, which translates in high potential brain damage. It was also noticed the presence of carboxylic acids (usually related to lipid hyperoxidation), production of reactive carbonyls, and proteins structural and functional alterations. Differences in protein conformation were also identified between control and disease samples and were mainly related with occurrence of protein aggregates.Some changes were also associated with oxidative cellular damage in disease samples.

In conclusion, FTIR has potential to be applied in future not only for cognitive impairment diagnosis but also for identification of disease stage and prognostic evaluation, besides assessment of disease developing risk for control subjects.