The association between 22 psychological cognitive factors and temporomandibular joint disorders:a Mendelian randomization study

Abstract

Abstract Background Although existing research suggests a broad association between psychological cognitive factors and TMD, the specific impact of psychiatric factors on TMD remains unknown, as does the causal relationship between them. Methods Utilizing summary statistics obtained from genome-wide association studies predominantly conducted on individuals of European ancestry, we employed a two-sample MR approach to estimate the causal and reverse causal effects of 22 psychological cognitive factors on TMD. Subsequently, for statistically significant findings, we performed multivariable MR analysis and bidirectional MR analysis after categorization to ascertain independent associations and explore potential reverse causation. Results We found that intelligence(OR: 0.731, 95%CI: 0.557–0.960), education(OR: 0.487, 95%CI: 0.368–0.644) and cognition(OR: 0.760, 95%CI: 0.586–0.986) were protective causal factors for TMD, with education(OR: 0.501, 95%CI: 0.307–0.818) having the independent association. And we found that major depression(OR: 2.116, 95%CI: 1.542–2.904), anxious feelings(OR: 6.014, 95%CI: 1.692–21.373), nervous feelings(OR: 14.019, 95%CI: 2.499–78.64), depressed feelings(OR: 20.905, 95%CI: 1.695–263.5), sensitivity(OR: 5.965, 95%CI: 1.471–24.19) and neuroticism (OR: 1.258, 95%CI: 1.101–1.438) were the factors that constituted harmful causal effects on TMD, with major depression(OR: 1.964, 95%CI: 1.320–2.920) having the independent relationship. These results were all robust to sensitivity analyses. We found no evidence on causal effects between other phychological cognitive factors and TMD, in either direction. Conclusions Our study demonstrated that intelligence, education, and cognition exert a protective influence on TMD, with education exhibiting an independent effect. Furthermore, we elucidated that major depression, anxious feelings, nervous feelings, depressed feelings, sensitivity, and neuroticism pose as risk factors for TMD development, with major depression being an independent predictor. These findings provide valuable insights into the causal relationship between 22 psychological cognitive factors and TMD.