Physiological effects of steroids can be estimated reasonably well because it can reasonably be supposed that few if any potential users are going to have significant pre-existing medical problems. But when trying to evaluate mental effects, that supposition has no basis. As Darkes (see farther below) and many others have pointed out, one of the chief failings of many studies of steroids and psychiatry is the failure to design the studies so that the cause-and-effect relationship is not tangled. While there are, in some reports, evidences of some possible correlation of steroid use and mental problems, what few if any of those studies address is which is cause and which effect .
The National Heart, Lung, and Blood Institute (NHLBI) recommended dosing for systemic prednisone, prednisolone, or methylprednisolone in pediatric patients whose asthma is uncontrolled by inhaled corticosteroids and long-acting bronchodilators is 1–2 mg/kg/day in single or divided doses. It is further recommended that short course, or "burst" therapy, be continued until the patient achieves a peak expiratory flow rate of 80% of his or her personal best or until symptoms resolve. This usually requires 3 to 10 days of treatment, although it can take longer. There is no evidence that tapering the dose after improvement will prevent a relapse.
The gains made by athletes in uncontrolled observations have been much more impressive. Weight gains of thirty or forty pounds, coupled with thirty percent increases in strength, are not unusual. Such case studies lack credibility because of the absence of scientific controls. However, it would be foolish to completely disregard such observations because the "subjects" have been highly trained and motivated see the articles on pharmacology of sport and sports medicine in the countries of the former Soviet Union for more information on anabolic steroids.