AFNI Not Recognizing My +tlrc Datasets – 'NO-DSET' Error

3dMVM cannot handle missing data. I recommend using 3dLMEr or 3dGLMM instead.

On a separate note, Years_OpioidUse and Years_StimulantUse are likely mediators of the age effect. If so, including them when examining age effects may be problematic. For more details, you may find this discussion helpful: Covariate Selection.

Gang Chen