Acually a good question. There is some reports that Ritalin may be benificial for Refractory depression, but the debate on that issue continues, as true effacacy has not yet been proven.
Ritalin does have a mechinism that does help with focus and alertness so I would not be supprised if it was effective for some forms of Depression. To what degree I can't say for sure.
Are you also medication resistant too?