Neuroimaging in mood disorders

Neuroimaging in mood disorders

It is not currently possible to diagnose depression or bipolar disorder with any neuroimaging technique. However, some progress is being made in mapping inefficient information processing in various circuits in mood disorders. In depression, the dorsolateral prefrontal cortex, associated with cognitive symptoms, may have reduced activity, and the amygdala, associated with various emotional symptoms including depressed mood, may have increased activity ( ).Figure 6-49 Furthermore, provocative testing of patients with mood disorders may provide some insight into malfunctioning of brain circuits exposed to environmental input, and thus required to process that information. For example, some studies of

Figure 6-49. . Neuroimaging studies of brain activationNeuroimaging of brain activation in depression suggest that resting activity in the dorsolateral prefrontal cortex (DLPFC) of depressed patients is low compared to that in nondepressed individuals (left, top and bottom), whereas resting activity in the amygdala and ventromedial prefrontal cortex (VMPFC) of depressed patients is high compared to that in nondepressed individuals (right, top and bottom).

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Figure 6-50. . EmotionalDepressed patient’s neuronal response to induced sadness versus happiness symptoms such as sadness or happiness are regulated by the ventromedial prefrontal cortex (VMPFC) and the amygdala, two regions in which activity is high in the resting state of depressed patients (left). Interestingly, provocative tests in which these emotions are induced show that neuronal activity in the amygdala is over-reactive to induced sadness (bottom right) but under-reactive to induced happiness (top right).

depressed patients show that their neuronal circuits at the level of the amygdala are over-reactive to induced sadness but under-reactive to induced happiness ( ). On the other hand, imagingFigure 6-50 of the orbitofrontal cortex of manic patients shows that they fail to appropriately activate this brain region in a test that requires them to suppress a response, suggesting problems with impulsivity associated with mania and with this specific brain region ( ). In general, theseFigure 6-51 neuroimaging findings support the mapping of symptoms to brain regions discussed earlier in this chapter, but much further work is currently in progress and must be completed before the results of neuroimaging can be applied to diagnostic or therapeutic decision making in clinical practice.

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Figure 6-51. . Impulsive symptoms of mania, such as riskMania patient’s neuronal response to no-go task taking and pressured speech, are related to activity in the orbitofrontal cortex (OFC). Neuroimaging data show that this brain region is hypoactive in mania (bottom right) versus healthy (bottom left) individuals during the no-go task, which is designed to test response inhibition.

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