Clinical Application RR Example

Example Registered Report Abstract - Clinical Application

Title

Magnetic Resonance Spectroscopy for Detecting Metabolic Alterations in Major Depressive Disorder: A Registered Report

Introduction

Background and motivation

Major Depressive Disorder (MDD) affects approximately 7% of the adult population and remains difficult to diagnose objectively. Previous studies suggest neurochemical abnormalities in MDD patients that could be detected through Magnetic Resonance Spectroscopy (MRS). However, findings have been inconsistent due to methodological variations and small sample sizes. This registered report outlines a confirmatory study designed to identify reliable metabolic biomarkers in the anterior cingulate cortex (ACC) that distinguish MDD patients from healthy controls.

Hypothesis

We hypothesize that MDD patients will show significantly reduced GABA/Cr ratios and elevated Glu/Cr ratios in the ACC compared to matched healthy controls, with effect sizes of d≥0.75 for GABA/Cr and d≥0.65 for Glu/Cr.

Methodology

We performed a systematic review of 15 MRS studies in MDD (cumulative n=423 MDD patients, n=379 controls) by querying PubMed with the keywords "Major Depressive Disorder"+"MR Spectroscopy".

Current status and Preliminary Results

The systematic review revealed consistent GABA deficits in the ACC with pooled effect sizes ranging from d=0.65-0.89. Meta-regression showed larger effects in medication-naïve patients (d=0.78, 95% CI [0.63-0.93]). Glutamate findings were more heterogeneous but suggested moderate elevations (d=0.62, 95% CI [0.46-0.78]) in ACC.

Plan and Outlook

Study Protocol

This confirmatory cross-sectional study will include 42 medication-naïve MDD patients (diagnosed using DSM-5 criteria, HAMD-17 score ≥18) and 42 age- and sex-matched healthy controls. Exclusion criteria include other psychiatric disorders, neurological disease, substance use disorder, and MRI contraindications.

All participants will undergo 3T MRS (Siemens MAGNETOM Prisma) with:

• MEGA-PRESS sequence for GABA (TE=68ms, TR=2000ms, 256 averages)
• PRESS sequence for other metabolites (TE=30ms, TR=2000ms, 128 averages)
• Voxel placement: 2×2×2cm³ in the dorsal ACC
• Additional T1-weighted imaging for tissue composition correction

All participants will complete:

• HAMD-17 and BDI-II for depression severity
• STAI for anxiety symptoms
• Structured clinical interview (SCID-5)
• Demographic and medical history questionnaires

Statistical Analysis Plan

Primary Outcomes

1. GABA/Cr ratio differences between MDD and control groups
2. Glu/Cr ratio differences between MDD and control groups

Secondary Outcomes

1. Correlation between GABA/Cr and depression severity
2. Correlation between Glu/Cr and depression severity
3. Exploratory analysis of other metabolites (NAA, Cho, mI)

Sample Size Justification

Based on our literature review, we estimate effect sizes of d=0.75 for GABA/Cr and d=0.65 for Glu/Cr. Power analysis indicates that 42 subjects per group will provide 90% power to detect both effects at α=0.025 (Bonferroni-corrected for two primary outcomes).

Statistical Methods

• Independent samples t-tests for between-group comparisons (with Bonferroni correction)
• ANCOVA with age, sex, and gray matter fraction as covariates
• Pearson correlations for metabolite-symptom associations
• ROC analysis to determine diagnostic utility