that the greater the gray matter density before treatment, the better 9 response to cognitive behavioral thera. so in a sense at least in this one study that definitely needs replication,im ageing can help predict treatment response. >> what is the link between genetics and treatment? >> sure, solisa brought up different days that biologically we can understand whether people respond differently to drugs or why they might be sensitive it turns out that as eric talked about earlier, genetic studies based on twin studies suggested that given the same trauma, about 30 to 40% of the risk for who develops ptsd versus without does not is genetically mediated tre ara mber of genes starting to come out, one is the serotonin transporter. the serotonin transporter has been associated in a number of studies looking at stress dependency or depression and ptsd. we had a study out last year showing from a campus shooting in illinois that women who had the risk alil, in this case the s verse of the serotonin transport were more likely to develop ptsd after the same expose sheer than women who hit other visio