Depression is primarily diagnosed via interviews and observations by specialists as objective biomarkers for the condition are yet to be established. Establishing such biomarkers could aid early diagnosis and treatment of the condition.
An electroencephalogram (EEG) is a test that measures electrical activity in the brain via electrodes attached to the scalp. Recent machine-learning studies indicate that EEG biomarkers can accurately distinguish between patients with depression and healthy controls.
However, until now, studies analyzing EEG data have been unable to detect signs of depression. The researchers behind the present study noted that this might be because such studies rely on brain activity that reflects long-term cognitive decline, whereas early diagnosis requires data from daily changes.
In the current study, researchers investigated how daily changes in EEG-recorded brain activity correlate with depressive tendencies. To do so, they analyzed data from 10 participants, including seven men and three women aged between 18 and 34 years old. Among them, nine were healthy, and one had previously been diagnosed with depression.
For the study, the participants were asked to record their brain activity via EEG for one minute each day over 14-26 days while at home. They were also asked to complete a self-report questionnaire that assesses different emotional states, including depression, dejection, fatigue, and inertia.
Ultimately, the researchers found that in many participants, the phase resetting rate (PRR)- the rate at which brain waves from different brain regions synchronize- increased with high levels of depressed mood at some frequencies yet decreased at others.
They write that their findings may facilitate early detection and treatment of depression. They noted, however, that for this, further studies over a longer time frame with more participants- including those with depression- are required.
“Nevertheless, PRR is currently the only candidate that can estimate changes in depressed mood in individuals who are not yet diagnosed as being depressed. [PPR thus] seems essential for early detection of depression and appears more promising than other candidates that can only discriminate EEG between patients with depression and healthy controls,” concluded the researchers in their paper.
Sources: Neuroscience News, Scientific Reports
