Complex sentence: A review article published in 2007 found psychostimulants may be effective in treatment-resistant depression with concomitant antidepressant therapy, but a more certain conclusion could not be drawn due to substantial deficiencies in the studies available for consideration, and the somewhat contradictory nature of their results.
Split into simpler sentences: A review article published in 2007 found psychostimulants may be effective in treatment-resistant depression with concomitant antidepressant therapy. A more certain conclusion could not be drawn due to substantial deficiencies in the studies available for consideration, and the somewhat contradictory nature of their results.