A pilot study testing for statistically significant blood biomarkers found in early-onset MDD: "Discovery of blood transcriptomic markers for depression in animal models and pilot validation in subjects with early-onset major depression"
[PDF], published by the online, open source journal Translational Psychiatry**
, April 2012, Volume 2.
Chronic stress gene transcripts and chronic stress in youths. Youths with depression had more exposure to maltreatment than did those who did not have any disorder (MeanMDD = 41.1±5.9 (s.d.) vs MeanND = 30.2±5.9 (s.d.), effect size = 1.74). CTQ*** Total score was correlated with 4 of the 26 gene transcripts at the level of a medium effect size or greater: CMAS, PSME1, PTP4A3 and IRF3. These markers were all derived from the chronic stress model (K. Pajer, et al., p. 7).
Despite over 30 years' research, there are currently no known "valid, reliable, selective and feasible biomarkers for MDD" (K. Pajer, et al., p. 1). The researchers monitored blood transcript, rather than serum protein, levels for the study. This study uniquely focuses on young people who experience early-onset MDD
. Early-onset MDD is statistically correlated to higher incidence of future episodes of MDD later in life.
In total, 53 young people between the ages of 15-19 were included in the study. Tested blood biomarkers focused on those gene transcripts with known functions in processes mediating neuronal damage, as well as those involved in immunoregulation and neurodegeneration. The first biomarker panel, consisting of 11 transcripts, differentiated young people with MDD versus those without any psychiatric diagnosis (ND), with genes belonging broadly to the categories associated with transcription, neurodevelopment, and neurodegeneration.
1) Robert Sapolsky's lecture
on clinical depression, also described as a major stress response [YT link].
2) LA Times article
on K. Pajer, et al. study, with quote by lead researcher, Eva Redei, PhD.
* Major Depressive Disorder.
** Translational Psychiatry
"explores the more translational area between the research in neuroscience and conceptually novel treatments.
*** Childhood Trauma Questionnaire; see p. 3 in attached PDF article.