Background: Using random-intercept cross-lagged panel models (RI-CLPM), researchers have concluded that within-individual need for cognition (WI-NFC) negatively affects subsequent within-individual anxiety and depression symptoms (WI-ADS). However, RI-CLPM may be susceptible to spurious results due to regression to the mean. We investigated the risk of spurious associations by fitting two different RI-CLPM:s and evaluating whether results were consistent. Methods: A traditional RI-CLPM, an alternative RI-CLPM where covariance between WI-NFC and WI-ADS at the same wave was replaced by a directional regression effect, as well as a stable trait, autoregressive trait, state (STARTS) model, were fitted to data from a representative community-dwelling Dutch sample.Results: Both the traditional and the alternative RI-CLPM indicated a negative effect of initial WI-NFC on subsequent WI-ADS. However, while the former effect implies a negative association the latter effect implies, contrarily, that an increase in WI-NFC predicted an increase in WI-ADS. The STARTS model indicated strong autoregressive effects but no cross-lagged effects between WI-NFC and WI-ADS.Limitations: Only data from a Dutch sample collected 2007-2018 were included. It is possible that findings would not generalize to other samples. Both NFC and ADS were self-rated. A large proportion of values were missing. Conclusion: Spurious effects may occur in RI-CLPM due to regression to the mean. Specifically, a cross-lagged effect of WI-NFC on subsequent WI-ADS, demonstrated in earlier research, may be spurious. Knowledge that it may not be possible to treat or prevent ADS through measures to increase NFC is of clinical relevance.