18. Subject has contra-indications to MRI scans or does not agree that (1) the scans are obtained for research purposes only and will not be evaluated by a qualified neuroradiologist; if an abnormality is present, this may well not be noticed by the doctors, scientists and other staff involved in the study and handling the MRI data; and that (2) if any of the staff involved in the study do suspect a relevant abnormality to be present in any of the scans, they will reveal this to the subject so that a further diagnostic workup can be conducted outside of the study.