I have a statistics question.

My experimental setup is the following:

Conditions:

cell age: young, old

treatment: control, drug

Different genome readouts (methylation, acetylation, ...) were taken for these conditions. The processed (e.g. CPM normalization) signal for each readout was organized into a matrix with rows equaling genomic location and columns equaling readout type/condition.

Using PCA for each readout I know that old vs. young separates control samples very well with most of the variance explained (~70%) for all readouts.

How can I test whether the drug significantly affects/alters the variance associated with cell age? I.e. say methylation changes in old vs young are reduced stronger by the drug than say acetylation changes?

Thank you!