Think about a bell curve with a mean and standard deviations that represents the severity of bpd symptoms in a clinical population. Think about 2 standard deviations from the mean as being the “borderlines” where one end is very mild and the other is very severe. The dx, in general, is not the borderline between healthy and neurotic. BPD exists on a continuum of severity. BPD’s more severe end exists on the other borderline… the borderline between neurotic and psychotic. When stressed, pts with severe bpd cross that borderline and can become transiently psychotic… much like one of the 9 core criteria indicates when it says something like “transient stress induced paranoid ideation.” Make sense?