Curiosity helps: Growth in need for cognition bidirectionally predicts future reduction in anxiety and depression symptoms across 10 years

• Lower level of need for cognition (NFC) predicted higher future anxiety and depression symptoms (ADS). • Likewise, within-person larger reduction in NFC forecasted greater future increase in ADS. • Within-person relations held after adjusting for between-person effects, regression to the mean, baseline scores, and socio-demographic variables. • Between persons, lower NFC correlated with higher ADS across all time-points. • All within-person causal and between-person correlational effect sizes ranged from moderate-to-large. Decreased motivational tendency to seek out, engage in, and enjoy investing in complex cognitive processes in a sustained manner (need for cognition; NFC) may be a predictor and consequence of heightened anxiety and depression symptoms (ADS). However, the majority of investigations on this topic have been cross-sectional, which hinders causal inferences. The current study thus determined the within -person relations between NFC and ADS by using random intercept cross-lagged panel model (RI-CLPM) and bivariate dual latent change score (BLCS) approaches to separate between- and within-person effects. RI-CLPM and BLCS also present with advantages of adjusting for regression to the mean, baseline scores, autoregressive and lagged effects, and minimizing measurement error. Community-dwelling adults ( n = 6750) completed the Mental Health Inventory-5 and trait-level NFC scales approximately every one year across 10 years. RI-CLPM showed that within persons, lower level of NFC predicted higher future level of ADS, and vice versa ( d = -0.852 to -0.498). Likewise, BLCS demonstrated that within persons, smaller change in NFC forecasted larger subsequent increase in ADS, and conversely ( d = -0.631 to -0.519). Findings remained after adjusting for socio-demographic covariates. Consistent with theories, findings suggested that the within-person level-to-future level and change-to-future change relations among NFC and ADS were bi-directional and negative, with moderate-to-large effect sizes. Targeting NFC may treat or prevent the emergence of depression and anxiety disorders. Such efforts may include augmenting or personalizing evidence-based cognitive-behavioral therapeutic strategies for individuals with or at-risk for heightened ADS.