Proteomics technologies have been widely used in the investigation of 
neurodegenerative and psychiatric disorders, and in particular in the detection 
of differences between healthy individuals and patients suffering from such 
diseases. Thus, brain and cerebrospinal fluid (CSF) samples from patients with 
Alzheimer's disease, Down syndrome, Pick's disease, Parkinson's disease, 
schizophrenia, and other disorders as well as brain and CSF from animals serving 
as models of neurological disorders have been analyzed by proteomics. 2-DE 
followed by MALDI-TOF-MS has been mainly applied as this proteomics approach 
provides the possibility of convenient quantification of protein levels and 
detection of post-translational modifications. About 330 unique proteins with 
deranged levels and modifications have been detected by proteomics approaches to 
be related to neurodegeneration and psychiatric disorders. They are mainly 
involved in metabolism pathways, cytoskeleton formation, signal transduction, 
guidance, detoxification, transport, and conformational changes. In this 
article, we provide a summary of the major contributions of proteomics 
technologies in the study of neurodegenerative and psychiatric diseases, in 
particular, in the detection of changes in protein levels and modifications 
related to these disorders.