Written by Charlotte Harrison, Science Writer.
Identifying the molecular changes associated with mental health disorders will pave the way for better diagnostics and treatments.
A study published in Translational Psychiatry shows that changes in miRNAs found in extracellular vesicles are associated with major depression, attention-deficit/hyperactivity disorder (ADHD) and anxiety disorders in young people. As such, the miRNAs might one day be used as a peripherally measured biomarker of centrally mediated mental health disorders.
The researchers analysed samples from 116 adolescent participants at two time points, 3 years apart. Extracellular vesicles were extracted from blood serum then characterized by size distribution and membrane proteins, and miRNAs were isolated and sequenced.
A longitudinal analysis of four participant groups that had different diagnostic trajectories — persistent diagnosis, first incidence, remitted and typically developing/control — did not show any changes in miRNA expression over time.
A cross-sectional analysis then compared individuals diagnosed with major depressive disorder, anxiety disorders and ADHD with individuals without a psychiatric diagnosis at each time point.
The researchers found that in the ADHD group there was an upregulation of miR-328-3p at the first timepoint only; in the major depression group, five miRNAs (miR-4433b-5p, miR-584-5p, miR-625-3p, miR-432-5p and miR-409-3p) were downregulated at the second time point only; and in the anxiety group, three miRNAs (miR-432-5p, miR-151a-5p and miR-584-5p) were downregulated at the second timepoint only.
The authors note that their results identified both previously observed and new differentially expressed miRNAs and their relationship with several mental health disorders. The identified miRNAs might regulate the expression of genes that are associated with mental health traits in genome-wide association studies.
To continue their work on the translation of extracellular vesicle miRNAs as biomarkers for mental health disorders, the researchers next plan to confirm their findings in larger cohorts and also study newly collected data from the same participants who are now adults.