Does Concerta have any effect on depression?

Hi, Stella!
Yes and no. It's a central nervous system stimulant that can help fight the fatigue, apathy, poor concentration, and general feelings of illness but doesn't directly treat or "cure" depression. It can give you an energy boost.
"Although the adjunctive use of psychostimulants like Ritalin or Concerta (methylphenidate) is still being investigated for the treatment of treatment-resistant depression, there is no clear evidence that methylphenidate is effective at easing the symptoms. Although some promising results were seen in case studies, controlled studies have not demonstrated significant improvement in patient outcomes. As such, most doctors do not recommend Ritalin as a first-line treatment for depression."
However, you might be interested in these user reviews from patients:
https://www.drugs.com/comments/methylphenidate/for-depression.html
Best regards,
Wildcat
PS, I've been taking methylphenidate as an adjunct to treatment with an antidepressant (bupropion) and a mood stabilizer (lamotrigine) for over four years.