Neurokinin (NK) 1 Antagonist for Pathological Aggression for Harmful, Impulsive, and Self-/Aggressive Behaviour

Inclusion Criteria: * are outpatients between 18 and 65 years old inclusive * meet diagnostic criteria for either Intermittent Explosive Disorder or the adult-modified criteria for Disruptive Mood Dysregulation Disorder (Appendix A) * have maintained a stable regimen of psychotropic medications (antidepressants, antipsychotics, anticonvulsants, and anxiolytics) for at least 4 weeks prior to study enrolment and throughout the duration of the treatment phase of the study * If participating in psychotherapy, must have been in stable treatment for at least 3 months prior to entry into the study, with no anticipation of change in the frequency of therapeutic sessions, or the therapeutic focus over the duration of the study * Have capacity with respect to medical decision-making and consent to participate * pass the TMS Assessment Safety Survey (TASS) MRI safety questionnaire Exclusion Criteria: * have a diagnosis of schizophrenia, schizoaffective disorder, schizophreniform disorder, delusional disorder, or other primary psychotic disorder * meet criteria for a current manic episode or hypomanic episode * have a diagnosis of dementia or other neurodegenerative illness affecting the central nervous system * have a history of substance dependence or abuse within the last 3 months * are pregnant or currently nursing\* * \*Patients will be tested before and after the study with a urine pregnancy test. * are taking contraindicated or interacting medications from product monograph of aprepitant * have an implanted intracranial device or pacemaker * have a diagnosis of severe hepatic insufficiency