Minor Physical Anomalies, Dermatoglyphic Asymmetries, and Cortisol Levels in Adolescents with Schizotypal Personality Disorder leaves some methodological doubt that carries over into results concerning the relationship between cortisol and schizotypal personality disorder.
This study was conducted over only one day and with some intelligent foresight the authors realized that many of these participants would be taking medications, and so asked those participants in the study to abstain from their medication only one day prior to the study. It probably would have been difficult to get the participants to abstain for more than one day prior to the tests, but the question remains is one day enough when some of those medications have effects that last longer than a couple of days? These medications were also more likely to be given to those with behavioral problems and so if they have some affect on cortisol were more likely to skew schizotypal and the other personality disorders group, rather than the normal group(Weinstein et al.,
619). It turns out in fact that methylphenidate does indeed influence the hypothalamic-pituitary-adrenal axis by increasing plasma ACTH (Appendrodt et al., 415). This increase in ACTH would result in an increase in cortisol release. Methylphenidate concentrations in the blood plasma have been shown to peak at 6.5 hours after ingestion, with not too quick a half life of 32.9 ng.h/mL and 3.9 hours (Modi et al., 379). Hence after 48 hours, 7% of the original methylphenidate would still be present in oneÃÂââÃÂìâÃÂâs system. This may or may not be enough to skew the schizotypal personality disorder group, since five of them had taken methylphenidate in the last month, and possibly even under 48 hours prior to the study. Therefore it is questionable whether or not the cortisol increase was due to medication in the schizotypal group or...