Assessing mood is inherently subjective.
– “How sad are you?”
– “. . .”
However, scientifically quantifiable means of determining the severity of mood disorders are on the rise. Through the cooperation of researchers of the United States, Europe, and Australia spanning from the University of Texas to Deakin University, a blood compound (BDNF) was identified as an indicator of bipolar mood swings.
Brain-derived neurotrophic factor (BDNF) is a protein that aids in the development and survival of neurons. BDNF works to promote growth of neurons and synapses in the brain, eyes, and kidneys among other places. This protein has important links to obesity, epilepsy, schizophrenia, and as seen in this study, bipolar disorder.
Bipolar disorder causes intense emotionally states (overly happy or extreme hopelessness) that last for unusually long periods of time. In a state of mania, one might be easily distracted, sleep very little, overestimate their personal abilities, and act impulsively on high risk high pleasure activities. During a depressive episode the person might feel tired, lack concentration, drastically change eating habits, and actively think of death or suicide.
The researchers of this study analyzed the data of 52 studies published from 2005 to 2015 that looked at levels BDNF circulating within 3,339 individuals in manic, depressive, or euthymic (moderately happy) states compared to 3,142 healthy control participants. The goal was to find a link between amount of BDNF in the blood and current manic or depressed signs. The meta-analysis showed BDNF levels significantly dropped during manic and depressed episodes (Hedges’ g = -0.57 and -0.93 respectively), while euthymia showed no change in BDNF.
Not only did BDNF decrease more with increasing severity of bipolar episode, but individuals treated for their manic episodes showed increases in BDNF with medication. The BDNF increase was not seen with depressive episode treatment, but this could be due to depression signs persisting through treatment (Read as: science is good at depressing people, but bad at cheering them up).
If further research finds that BDNF levels are decreasing before depressive or manic episodes, this protein could be used as a forecaster of bipolar mood jumps. BDNF currently shows the most promise as a biomarker for activity.
In conjunction with other blood assays, BDNF may be able to help determine if in fact someone is bipolar, how severe their mood swings are, and give a more numeric answer to “how sad are you?”.
Brisa S. Fernandes, Marc L. Molendijk, Cristiano A. Köhler, Jair C. Soares, Cláudio Manuel G. S. Leite, Rodrigo Machado-Vieira, Thamara L. Ribeiro, Jéssica C. Silva, Paulo M. G. Sales, João Quevedo, Viola Oertel-Knöchel, Eduard Vieta, Ana González-Pinto, Michael Berkand, André F. Carvalho. Peripheral brain-derived neurotrophic factor (BDNF) as a biomarker in bipolar disorder: a meta-analysis of 52 studies. BioMed Central Medicine, 2015.