Brain scans come in a variety of types. Some investigate brain structures, for example, “CT” or “CAT” scans (“computerized axial tomography”) or “MRI” scans (magnetic resonance imaging). Other types of scans investigate how the brain functions, such as “functional MRI” or “MRS” (magnetic resonance spectroscopy) scans. There are two reasons that individuals or their clinicians may be interested in brain scans. One reason is clinical, and the other reason is to contribute to research.
With regard to the clinical reason for brain scans, they are often used to be sure that there is no brain injury or abnormality that could be responsible for bipolar symptoms—for instance, a tumor or a stroke or multiple sclerosis. These causes are rare, and brain scans are often done with the clinician thinking, “I’m don’t think so but just in case…” The cases where there actually is a structural brain problem that the scans could detect are so rare that clinical practice guidelines usually don’t recommend them for routine use.
In the research setting, brain scans are being used to attempt to identify structures or chemical processes that underlie the symptoms of bipolar disorder. In these cases, the clinician informs the individual that a particular scan he or she is suggesting a brain scan specifically for research purposes, and that typically no information specific to their individual diagnosis or treatment should be expected—the individual is agreeing to a brain scan to further the cause of identifying mechanisms and treatments for bipolar symptoms. In these situations a formal informed consent form is signed after the clinician describes not only the benefits but also the risks of the procedure.
However, individuals should be aware that there are no scans that can “diagnose” bipolar disorder directly. We hope that in the future there will be. Currently, a bipolar disorder diagnosis is made based on history and clinical interview. Beware the clinician who wants to order a brain scan “to see if you have bipolar disorder.”