I think if your wife is supplementing with DHEA that it would be wise to consider having her hormone levels tested again in about 3 months to verify that they are all still within the normal range and balanced.
DHEA can convert to both estrogen and testosterone and in addition to concern about balancing the estrogen and progesterone, don't forget there was a study which found high and low levels of testosterone were associated with MRI findings in women.
Sex hormones modulate brain damage in multiple sclerosis: MRI evidence
Totally speculative on my part, but I think it's possible people may feel better with DHEA (without the progesterone) because DHEA just might be a factor in the MS disease process (of course, progesterone might be too--but I think you mentioned your wife's progesterone level was within the normal range).
Some reasons for the speculation: DHEA is a powerful immune modulator, it could explain several of the "immunological" findings in MS, it protects against viruses and bacteria, including a viral encephalitis (animal studies), it could explain the neurodegeneration in MS (it opposes cortisol--I just have to put in this
an augmented plasma cortisol:DHEAS ratio, widely recognized as an unfavorable prognostic index for the risk of neurodegeneration
from this abstract
), it tends to be low in people with MS and it starts to decline during prime time for a diagnosis of MS--between the ages of 20 and 40. So indeed, I do think someone with MS and a low level of DHEA just might feel better bringing their DHEA level to the normal range. The two Phase I clinical trials of DHEA for MS had positive outcomes.
Now, the links don't seem to be working on my end and I can't figure out why, but I'm giving up. If anyone wants to read the info, you can type the titles into Pub Med. The title of the abstract for the quote is "Menopausal transition: A possible risk factor for brain pathologic events