This experimental study suggests that continued use of methylphenidate hydrochloride (Ritalin) in young animals is associated with a delay in the pace of normal puberty, based on hormonal measurements and rate of testicular growth. Should this be a cause for concern for the use of this drug in humans? The eventual changes expected during puberty still occurred and the authors themselves note that ‘the effects were transient and no permanent deficits were found', including normal testicular size at the end of the study. They note the need for further studies in humans.
There are several important criticisms of this study. A major weakness in experimental design is the absence of a further treatment group given a chemically different behaviour altering treatment. This would have given insight into whether or not the changes observed are simply due to a change in behaviour pattern, as suggested by the observation that effects are transient, rather than to a harmful chemical effect of the treatment.
This possible effect of behaviour change alone was reported in the same journal [PNAS] the previous week [12th September, 2011] in a study by Gettler and colleagues noting that testosterone levels decrease in men who take part in child care. The authors also provide no information on important potential consequences of their findings. For example, it would have been important to know whether or not there was any impact on intellectual or psychological development or on fertility.
© DRJ Singer
© DRJ Singer