The present invention relates to a Raman spectroscopy method for determining protein structure associated with global cognitive deterioration in Alzheimer's disease from the Raman spectroscopic analysis of a human blood sample, preferably of a human blood plasma sample, comprising obtaining at least one spectral value of at least one of the Raman spectrum regions comprised between 1600-1700 cm−1, between 910-980 cm−1, between 730-760 cm−1 and/or between 390-450 cm−1, and where said spectral value allows obtaining an indication of the presence or absence of protein structure associated with a condition of Alzheimer's disease. The present invention also relates to a method for the infrared spectroscopic analysis of a blood sample, by means of additionally obtaining at least one spectral value of at least one of the infrared spectrum regions comprised between 1600 and 1700 cm−1, and/or between 1000 and 1150 cm−1 and/or between 1140 and 1190 cm−1. Optionally, the Raman spectroscopy method further comprises the infrared spectroscopic analysis of the same blood sample. The invention also relates to a diagnostic method for diagnosing Alzheimer's disease comprising measuring a Raman spectrum and/or an infrared spectrum of a plasma sample.
RAMAN, INFRARED, OR RAMAN-INFRARED ANALYSIS OF PERIPHERAL BLOOD PLASMA PROTEIN STRUCTURE AND ITS RELATION TO COGNITIVE DEVELOPMENT IN ALZHEIMER'S DISEASE