Objective:

To investigate peripheral blood expression of seven candidate genes in adults with and without depressive disorders in the UAE.

Approach:

• Study Design: A case-control study involving 49 adults with depressive disorders and 49 non-depressed controls.
• Assessment Tools: Participants were assessed using the Beck Depression Inventory-II and Patient Health Questionnaire-9.
• Gene Expression Measurement: Peripheral blood expression of seven genes was measured by quantitative real-time PCR, normalized to GAPDH.
• Statistical Analysis: Analyses included Mann-Whitney U tests, principal component analysis, fold-change estimation, and receiver operating characteristic analysis.

Key Findings:

• CADM1 showed modest upregulation in the depressive disorder group (1.30-fold; Mann-Whitney p = 0.049, uncorrected).
• Principal component analysis revealed an unadjusted PC2 difference (p = 0.006), driven by CADM1 and RAPH1, that did not survive age adjustment (MANCOVA p = 0.156).
• CADM1 correlated negatively with depression severity (BDI-II ρ = −0.280, p = 0.005), with the signal strengthening across severity strata.
• The CADM1 area under the receiver operating characteristic curve was 0.616, indicating no diagnostic utility.

Interpretation:

The findings indicate that CADM1 may warrant further investigation in depressive disorders, but the results are not robust enough for clinical application.

Limitations:

• Small sample size.
• Mean age difference of 13 years between groups.
• Unmeasured confounders may affect results.

Conclusion:

The study provides preliminary data on gene expression related to depression in a UAE population, highlighting the need for validation in larger, age-matched studies.