Neuroelectrophysiological clinical exploration of reward expectation and sensitivity abnormalities in adolescent melancholic MDD.
Level 4 - case-series / case-control
Cross-sectional case-control comparison (Experiment 1) and uncontrolled open-label pre-post case series (Experiment 2).
PubMed 42285528 · doi:10.1016/j.jad.2026.122128
What was done
The study conducted two experiments in adolescents. Experiment 1 compared 91 patients with major depressive disorder (45 with melancholic MDD [mMDD] and 46 with non-melancholic MDD [NmMDD]) against 40 healthy controls using clinical symptom scales and event-related potentials (ERPs) measuring stimulus-preceding negativity (SPN) and reward positivity (RewP). Experiment 2 enrolled 30 adolescent mMDD patients who received a 2-week course of open-label deep transcranial magnetic stimulation (dTMS) targeting the medial prefrontal cortex, assessing pre- and post-intervention clinical symptoms, ERP components, and power spectral density.
What was found
In Experiment 1, adolescents with mMDD demonstrated significantly higher depression, anxiety, and anhedonia compared to NmMDD. Depressed patients exhibited higher SPN and lower RewP amplitudes compared to controls, with mMDD patients showing lower RewP than NmMDD patients. In patients, SPN positively correlated with anhedonia (r = 0.437, p < 0.05), while RewP negatively correlated with anhedonia (r = -0.520, p < 0.01). In Experiment 2, significant pre-post differences were observed after 2 weeks of dTMS for clinical symptoms, SPN, and RewP amplitudes (p < 0.05), as well as increased delta-band and theta-band power at the Fz electrode (p < 0.05). Exact numerical values for clinical scale changes and ERP amplitudes were not reported in the abstract.
Why it matters
This study links reward-processing ERP indices (SPN and RewP) directly to anhedonia severity in adolescent melancholic depression. It also provides preliminary, exploratory neurophysiological data for medial prefrontal cortex-targeted dTMS in this population.
Limits
The interventional phase was open-label and uncontrolled (no sham or waitlist arm), preventing causal attribution of symptom relief or ERP changes to dTMS rather than placebo effects or natural recovery. Sample sizes were small (n = 30 in the interventional arm), the intervention duration was brief (2 weeks) without reported long-term follow-up, and the abstract omits baseline-to-endpoint effect sizes and absolute numbers.
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