GDF15 and Alzheimer disease: In this study, we observed that: (i) GDF15 is expressed and processed in human brain areas; (ii) GDF15 appears to be predominantly expressed by neurons; (iii) in some areas (frontal cortex and hippocampus) the processing into the mature form seems to be higher for AD patients with respect to age-matched non-demented subjects; (iv) accordingly, a lower expression level of representative OXPHOS proteins was found in AD samples with respect to non-demented subjects; v.