Hyperitensities refer to areas of high intensity on particular types of magnetic resonance imaging scans of the human brain. These small regions of high intensity are observed on T2 images within cerebral white matter or subcortical gray matter. They are usually seen in normal aging but also in a number of neurological and psychiatric illnesses. For example deep white matter hyperintensites are 2.5 - 3 times for likely to occur in bipolar disorder and major depressive disorder than control subjects. 
Hyperintensities are commonly divided into 3 types depending on the region of the brain where they are found. Deep white matter hyperintensites occur deep within white matter, periventricular white matter hyperintensities occur adjacent to the lateral ventricles and subcortical hyperintensities occur in the basal ganglia.
- ↑ Kempton, M.J., Geddes, J.R, Ettinger, U. et. al. (2008). "Meta-analysis, Database, and Meta-regression of 98 Structural Imaging Studies in Bipolar Disorder," Archives of General Psychiatry, 65:1017–1032 see also MRI database at www.bipolardatabase.org.
- ↑ Videbech, P (1997). "MRI findings in patients with affective disorder: a meta-analysis," Acta Psychiatrica Scandinavica, 96:157–168.
- ↑ Thomas, A.J., Perry, R., Barber, R., Kalaria, R.N., O’Brien, J.T. (2002). "Pathologies and pathological mechanisms for white matter hyperintensities in depression," Ann N Y Acad Sci., 977:333–339.