Three-way interactions with longitudinal data

#1
Hi there,

We are trying to examine whether carrying the risk gene for Alzheimer's disease (E4), moderates the effect of a continuous predictor over time (c.RNT#c.Time), on global cognition. In other words, "does carrying (or not carrying) the E4 allele moderate the effect of RNT on global cognition, over time".

I am using Stata, and my simplified code is:
mixed global c.RNT##c.time##i.E4

As I have never done this before, I wondered if someone would be able to advice on (1) whether my code is correct, and (2) how I would interpret the results, as below:

E4#c.RNT#c.Time coefficient = -0.07 p = 0.036

Thanks!

Lise