Brain imaging in psychiatry: what has it done for the patient?

The need for brain imaging in clinical psychiatry

Aims and Method

To explore clinical indications for, and results of, brain imaging in general adult psychiatry. We reviewed the 100 most recent uses of brain imaging on in-patients at the Department of General Adult Psychiatry, Mater Misericordiae University Hospital, Dublin.

Results

Patients were of a mean age of 55.3 years. the most common indications for brain scans were cognitive impairment (33%) and other neurological concerns (e.g. seizures; 30%). Overall, 47% of scans were abnormal, with ischaemia (17%) and atrophy (10%) being the most common abnormalities. Patients with abnormal scans were older than those with normal scans (mean age 61.9 and 48.7 years respectively; P<0.001).

Clinical Implications

A high proportion of brain scans demonstrate abnormalities in general adult psychiatry patients, especially among older patients.

Mapping brain function in freely moving subjects

Expression of many fundamental mammalian behaviors such as, for example, aggression, mating, foraging or social behaviors, depend on locomotor activity. A central dilemma in the functional neuroimaging of these behaviors has been the fact that conventional neuroimaging techniques generally rely on immobilization of the subject, which extinguishes all but the simplest activity. Ideally, imaging could occur in freely moving subjects, while presenting minimal interference with the subject's natural behavior. Here we provide an overview of several approaches that have been undertaken in the past to achieve this aim in both tethered and freely moving animals, as well as in nonrestrained human subjects. Applications of specific radiotracers to single photon emission computed tomography and positron emission tomography are discussed in which brain activation is imaged after completion of the behavioral task and capture of the tracer. Potential applications to clinical neuropsychiatry are discussed, as well as challenges inherent to constraint-free functional neuroimaging. Future applications of these methods promise to increase our understanding of the neural circuits underlying mammalian behavior in health and disease.