But, there are other people who consciously dissociate themselves from the trauma either while it is happening or later and those memories become repressed or lost. The consequence of the dysfunction in the Broca's area of the cortex is an impairment in the ability to process in explicit thought memories. Much of what we think when we are consciously paying attention to our thoughts is mediated through words and language. It appears that there is no disturbance in implicit memory, but the disturbance is in explicit memory, the ability to recollect the details. It really is best determined by a clinical interview, a careful review of the history and the symptoms that are involved.
Many clinicians do use scaled assessment tests to measure the variables.
But, essentially, once the history of the trauma is clear then clinically the diagnosis and the aspects of the diagnosis become clear. There are statistical differences that have been demonstrated on MRI in groups of individuals. But these tests are not useful for individual cases at this time. It sounds like you have a good light side. And, see if you can help your friend to find professional guidance and care.