A recent study investigated the effect of psychostimulants modafinil, atomoxetine, and guanfacine on the differentiation of mesenchymal stem cells to osteoblasts and on their cell functions, including migration. Researchers determined that the 3 medications commonly used to treat attention-deficit/hyperactivity disorder (ADHD) negatively affect hMSC differentiation to bone-forming osteoblasts and cell migration through different intracellular pathways.(1)