Studies have already established links between low levels of mature brain-derived neurotrophic factor (mBDNF) and depression, but this is the first time the three forms of the BDNF protein have been differentiated in blood samples. The mature form has a protective effect on the brain and supports neuron growth, but the other two forms attach to different receptors. They are known to cause inflammation and nerve damage. The UniSA scientists developed a kit that can distinguish between the three forms, and their findings, in collaboration with the University of Adelaide in Australia and Kunming Medical University in China, have been published in the Journal of Psychiatric Research. They say there is strong evidence to suggest that psychological stress decreases mBDNF, which in turn leads to depression.
About the Study
Over 200 people participated in the study, including 90 patients with clinical depression and 15 with bipolar disorder. According to the researchers, the more severe the depression, the lower the levels of mBDNF were in the patients’ blood. Additionally, mature BDNF levels in patients who weren’t on antidepressants were lower than patients who were taking antidepressants. However, there was no difference in mBDNF levels between 14 people with a history of suicide attempts and the 96 people in the control group. One of the study authors, neuroscientist and biochemist Larisa Bobrovskaya, PhD, who is an associate professor in clinical health sciences at UniSA, says the findings didn’t come as a surprise. “Previous studies have shown similar associations between low levels of serum BDNF and depression and bipolar disorder; however many of these studies used commercially available assays which are not very specific,” she says. “We have used a highly specific assay that shows negligible cross reactivity with similar molecules in the blood.” Bobrovskaya notes some limitations with the study. “We have only had a relatively small number of patients, so our findings need to be confirmed in a larger population of patients,” she says. Further research should focus on developing a panel of promising biomarkers that can assist clinical decision-making, she adds, because the possibility of developing one single biomarker for assessment of both depression and bipolar disorder is low due to their multifactorial nature. “Currently, the diagnosis of depression and bipolar disorder is based on a variety of clinical symptoms; such [an] approach is quite subjective and can lead to misdiagnosis and poor treatment outcomes,” Bobrovskaya says. “Developing objective biological markers for depression and bipolar disorders would be a valuable addition to the diagnostic algorithm and personalized treatment strategy in clinical practice.”
Depression and Bipolar Disorder
Millions of people around the world are affected by mood disorders, but research estimates that around one third of people diagnosed with depression are resistant to antidepressants. While the exact reasons for this are still undetermined, BDNF imbalances might be a factor. Major depressive disorder or clinical depression, most commonly known simply as depression, is one of the most common mood disorders. To be diagnosed with depression, you must have some of the common symptoms for at least two weeks. According to the National Institute of Mental Health (NIMH), these include persistent sad, anxious, or “empty” mood, feelings of hopelessness, irritability, feelings of guilt or worthlessness, decreased energy or fatigue, and thoughts of death or suicide, or suicide attempts. The NIMH includes bipolar disorder in its list of types of depression, while noting that it is a different mood disorder. Someone with bipolar disorder experiences episodes of extremely low mood that meet the criteria for major depression (“bipolar depression”)—but they also experience extreme high moods (“mania”) or a less severe form (“hypomania”). “Bipolar disorder, also known as manic-depressive illness, is a brain disorder that causes significant shifts in a person’s mood, energy, and ability to function,” says Aron Tendler, MD, chief medical officer of Brainsway. “Different from the normal ups and downs that everyone goes through, bipolar disorder impairs functioning and frequently results in hospitalization.” The symptoms of bipolar disorder vary from person to person, Dr. Tendler adds, but everyone experiences at least one episode of abnormal and persistently elevated, expansive, or irritable mood with increased energy lasting at least one week. “During the episode, patients may exhibit grandiosity, decreased need for sleep, increased or pressured manner, distractibility with poorly connected thought processes, psychomotor restlessness, and increased involvement in risky pleasurable activities,” Dr. Tendler explains. “Patients may suffer from comorbid anxiety or depression, which makes it harder for someone to identify what they’re dealing with.”
Diagnosing Bipolar Disorder
It can be difficult to diagnose bipolar disorder, because a person needs to have experienced a manic or hypomanic episode, but they may go an extended period of time without experiencing symptoms. “Manic episodes consist of more reckless behavior resulting in hospitalization or arrests, while hypomanic episodes are milder,” Dr. Tendler explains. “In either case, the person can also experience depression at the same time of the mania, which is a mixed episode. Unfortunately, bipolar disorder and depression often go hand in hand, in that bipolar patients characteristically exhibit discrete depressive episodes much more frequently than they exhibit manias.” It can also take time to find the right treatment for bipolar disorder, because the symptoms vary and patients frequently lack insight, which makes the assessment of progress a challenge. “Treatment for bipolar disorder frequently requires a combination of different methods, including several mood stabilizing medications along with careful symptom and sleep tracking,” Dr. Tendler says. Initially, you may feel uncomfortable talking to your doctor about your mental health, but it’s an important first step. With the right support and treatment, including self-care habits, you can start to feel better and look forward to a brighter future.
