Electroencephalogram (EEG), a relatively inexpensive, non-invasive method of measuring the electrical activity in the brain, may be used to promote the early detection and treatment of depression (1^✔ ✔Trusted Source
Brainwave activities reflecting depressed mood: a pilot study

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EEG – A Potential Diagnostic Tool to Identify Depression in a Healthy Person

Depression is a common but serious mental disorder that requires early diagnosis and treatment; however, it is currently difficult to do so.

The participants of this study were instructed to measure their EEG for 1 minute every day at home across two to four weeks to investigate its relationship to the intensity of their depressed mood.

The results demonstrated that the occurrence of phase resetting for many participants, in which brain waves from different brain regions synchronize, increased with high levels of depressed mood at certain frequencies but decreased at other frequencies.