Mental Health

Combined predictive value of TyG index and PLR for mental health in Chinese adults: A machine learning approach.

TL;DR

The TyG index and PLR are independently and jointly associated with mental health indicators in Chinese adults, and their combination identified by LASSO regression (AUC = 0.744) may enhance the ability to identify individuals at elevated risk for mental health problems.

Key Findings

The TyG index was positively associated with multiple SCL-90 mental health dimensions in Chinese adults.

  • Associations were found with SCL-90 total score, somatization, interpersonal sensitivity, depression, anxiety, and hostility (P < 0.05).
  • Data were drawn from 725 adults at Qilu Hospital of Shandong University.
  • Mental health was evaluated using the Symptom Checklist-90 (SCL-90).
  • The TyG index was calculated from fasting blood samples.

The platelet-to-lymphocyte ratio (PLR) showed positive associations with mental health dimensions similar to the TyG index, but also extended to additional domains.

  • PLR was associated with the same dimensions as the TyG index (P < 0.05).
  • PLR was additionally associated with phobic anxiety and psychoticism (P < 0.05), which the TyG index was not.
  • PLR was not significantly associated with obsessive-compulsive symptoms or paranoid ideation.
  • Both PLR and TyG index were calculated from fasting blood samples.

Individuals in the high-TyG/high-PLR combined group had significantly higher scores across nearly all SCL-90 dimensions compared to other groups.

  • The high-TyG/high-PLR group had significantly higher scores across all SCL-90 dimensions (P < 0.05), except for obsessive-compulsive symptoms and paranoid ideation.
  • This finding suggests a synergistic or additive effect when both biomarkers are elevated simultaneously.
  • The analysis compared groups defined by combined TyG and PLR levels.

Among six machine learning classifiers evaluated, LASSO regression demonstrated the best overall predictive performance for mental health problems.

  • LASSO regression achieved an AUC of 0.744.
  • LASSO showed balanced sensitivity, specificity, F1-score, and MCC.
  • Six machine learning classifiers were compared, using an 80/20 train-test split with cross-validation.
  • Multiple performance metrics including AUC, sensitivity, specificity, and MCC were reported.
  • Compared with traditional logistic regression, machine learning models showed superior discriminative ability and enabled the assessment of variable importance.

PLR and the TyG index were identified as the strongest positive predictors of mental health problems in the LASSO regression model.

  • LASSO regression was applied specifically to identify key predictors among all variables.
  • Both PLR and TyG index were identified as the strongest positive predictors.
  • This finding supports the utility of these two biomarkers as a pair in predictive applications.

Traditional logistic regression and linear regression were used to evaluate independent associations of TyG and PLR with overall and domain-specific mental health.

  • Linear regression evaluated associations with overall SCL-90 scores.
  • Logistic regression evaluated domain-specific mental health outcomes.
  • The sample consisted of 725 adults from a single hospital center (Qilu Hospital of Shandong University).
  • Fasting blood samples were used to calculate both biomarkers.

What This Means

This research suggests that two blood-based markers — the triglyceride-glucose (TyG) index, which reflects insulin resistance, and the platelet-to-lymphocyte ratio (PLR), which reflects inflammation — are each independently linked to poorer mental health in Chinese adults. The study analyzed data from 725 adults and used a widely recognized mental health questionnaire (SCL-90) to assess symptoms across multiple dimensions including depression, anxiety, hostility, and others. People with high levels of both markers simultaneously had significantly worse scores across nearly all mental health dimensions measured. The researchers also tested whether combining these two biomarkers could help predict who is at elevated risk for mental health problems, using both traditional statistical methods and six machine learning approaches. A method called LASSO regression performed best, achieving an AUC (a measure of predictive accuracy) of 0.744, and identified PLR and the TyG index as the strongest predictors. Machine learning models generally outperformed traditional logistic regression in distinguishing individuals with mental health problems from those without. This research suggests that routinely collected blood test results — specifically markers of metabolic and inflammatory status — may carry information relevant to mental health risk. The combination of the TyG index and PLR could potentially serve as a low-cost screening tool to help identify adults who may benefit from further mental health assessment, though the findings come from a single hospital in China and would need to be validated in broader and more diverse populations before clinical application.

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Citation

Zhou J, Yin S, Xue S, Sun C, Zhao Y. (2026). Combined predictive value of TyG index and PLR for mental health in Chinese adults: A machine learning approach.. PloS one. https://doi.org/10.1371/journal.pone.0355937