Abusing MDMA could possibly make her more depressed. However, if she only does it maybe once every few weeks, then it might make her happier. MDMA, isn't dangerous unless used too frequently. The high you get from MDMA is from a "flood" of serotonin. When you do it too frequently, your serotonin levels are too low, and not only will you get diminished effects, but it will also damage your serotonin receptors, theoretically, making you physically unable to be a certain level of "happy". If MDMA is used properly, it can essentially be an anti-depressant that doesn't cause physical damage. Also "speed" is a slang term for amphetamines. MDMA is an methlyamphetamine, so technically MDMA could be "speed". So, most likely she'll be fine... Unless she starts taking MDMA very frequently, there's nothing to worry about.
Lots of experience with MDMA and other drugs. I always do lots of research about the drugs I take so I know exactly what i'm doing to myself, and what that potential risks are.