The short answer is that we do not yet know. There is not yet adequate evidence to identify mental illnesses by way of MRI brains scan or PET scan. (CT scans have been replaced by MRIs for detailed brain imagining.)

There have been many small studies over the years trying to answer your question. Studies are ongoing. This article explains in non-technical terms why past studies are insufficient to come to reliable conclusions and what is happening to try to get answers to questions like yours:

https://news.yahoo.com/george-santos-married-woman-while-161923713.html?guccounter=1&guce_referrer=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS8&guce_referrer_sig=AQAAAM7gyZ-j7rRPH_Mslo4CKHIALYgVLdSvFlezFrMcwSa1x9b9X10uzkzrVrSNAQdaltWrRrfFx2dfHoXncbKBAoeUlV-lsSBj6J1ZYRepJENCl8lY5DtZwI8eZQ7DVGHBX1G5xl6yRHti1_VgtSi2QH0Ol7vkN4g5TDIWifZjvjIV