Johnson finally returned to elected office in 1850, when he was elected to the Kentucky House of Representatives. By this time, however, his physical and mental health was already failing. On November 9, the "Louisville Daily Journal" reported that "Col. R. M. Johnson is laboring under an attack of dementia, which renders him totally unfit for business. It is painful to see him on the floor attempting to discharge the duties of a member. He is incapable of properly exercising his physical or mental powers."