Blood biomarkers for neuropsychiatric diseases

Abstract

Diagnosis of Alzheimer’s disease (AD) at an early stage is relatively difficult because cognitive impairments are seen not only in early-stage AD but also in other neuropsychiatric diseases, such as geriatric depression and other neurodegenerative disorders, for which the treatments and prognoses are markedly different. Cognitive impairments are also seen in various psychiatric diseases, such as schizophrenia1 and bipolar disorder.2 Because several methods have been developed for measuring cognitive function in neuropsychiatric diseases, we need to find biomarkers reflecting the etiology of cognitive impairments in the near future. Blood biomarkers are useful as blood samples are relatively easy to collect and stable for long-term storage. Using high-throughput instruments, many genes and proteins can be examined simultaneously and quickly and are easy to examine repeatedly in the progress of disease. Although there are several promising blood biomarkers for diagnosis of neuropsychiatric diseases, few biomarkers are known to be associated with cognitive function. Further research is needed to find blood biomarkers for cognitive function of neuropsychiatric diseases. In this issue, Sao et al. present a new blood biomarker for AD: Myocyte-enhancer factor 2C (MEF2C) mRNA expression in leukocytes was significantly decreased in AD patients and this decrement correlated positively with cognitive impairment.3 MEF2C, mainly involved in inflammatory processes, has been associated with the development of AD in a large-scale genome-wide association study.4 MEF2C mRNA expression may offer a biomarker for not only diagnosis but also cognitive impairments in AD. Biomarkers for AD and its cognitive function now represent an active topic of major importance for basic research, clinical diagnosis, and therapeutic options in the fields of neuropsychiatry and neuroscience. Although further validation with larger sample sizes is needed, we are pleased to be able to introduce this paper as another step toward novel biomarkers for AD and its cognitive function.