Probabilistic Depression Detection from Textual Time Series

Accurate and interpretable predictions of depression severity are essential for clinical decision support, yet existing models often lack uncertainty estimates and temporal interpretability. We propose PTTSD, a Probabilistic framework for Depression Detection from clinical interview utterance sequences that predicts PHQ-8 scores while modeling calibrated uncertainty. PTTSD includes sequence-to-sequence and sequence-to-one variants, both combining LSTMs, self-attention, and residual connections with Gaussian or Student's-t output heads trained via negative log-likelihood. The sequence-to-sequence variant enables temporal analysis of how predictive confidence evolves over an interview, despite the target being a single session-level score. Evaluated on E-DAIC and DAIC-WOZ, PTTSD achieves competitive performance among text-only systems (e.g., MAE = 3.85 on E-DAIC, 3.55 on DAIC) and produces well-calibrated prediction intervals. Ablations confirm the value of attention and probabilistic modeling, while a three-part calibration analysis and qualitative case studies highlight the clinical relevance of uncertaintyaware prediction. E-DAIC E-DAIC seq-to-one (MentalBERT) vs. seq-to-seq (MentalBERT) MAE 4.18 4.20 -0.594 0.591 ns E-DAIC seq-to-one (MentalBERT) vs. seq-to-one (MiniLM) MAE 4.18 4.58 -1.379 0.300 ns E-DAIC seq-to-one (MentalBERT) vs. seq-to-seq (MiniLM) MAE 4.18 3.85 +8.927 0.001 * * E-DAIC seq-to-seq (MentalBERT) vs. seq-to-one (MiniLM) MAE 4.20 4.58 -1.314 0.319 ns E-DAIC seq-to-seq (MentalBERT) vs. seq-to-seq (MiniLM) MAE 4.20 3.85 +12.124 <0.001 * * * E-DAIC seq-to-one (MiniLM) vs. seq-to-seq (MiniLM) MAE 4.58 3.85 +2.521 0.126 ns E-DAIC seq-to-one (MentalBERT) vs. seq-to-seq (MentalBERT) RMSE 5.23 5.39 -1.816 0.158 ns E-DAIC seq-to-one (MentalBERT) vs. seq-to-one (MiniLM) RMSE 5.23 5.87 -1.193 0.351 ns E-DAIC seq-to-one (MentalBERT) vs. seq-to-seq (MiniLM) RMSE 5.23 4.52 +3.062 0.071 † E-DAIC seq-to-seq (MentalBERT) vs. seq-to-one (MiniLM) RMSE 5.39 5.87 -0.900 0.462 ns E-DAIC seq-to-seq (MentalBERT) vs. seq-to-seq (MiniLM) RMSE 5.39 4.52 +3.880 0.053 † E-DAIC seq-to-one (MiniLM) vs. seq-to-seq (MiniLM) RMSE 5.87 4.52 +2.349 0.111 ns