Neuroimaging studies

Since functional outcome and risk of recurrent stroke are, in part, predictable based on the pathophysiologic subtype of stroke, the ability to accurately classify patients based on emergency clinical and imaging data would provide valuable predictive information. Unfortunately, misclassifications of stroke subtypes based on clinical data and a noncontrast CT scan are common. The final subtyping of stroke is made with all available clinical data, but is heavily influenced by neuroimaging studies that identify the location, size, and vascular distribution of the infarct, or that establish that the arteries supplying the region of stroke are stenotic or occluded. 

Depression is not the only clinical condition in which placebo effects have been linked to changes in the brain. Changes in brain activity have also been shown in neuroimaging studies of placebo analgesics, the most influential of which was reported by a team of researchers led by Tor Wager, a neuroscientist at Columbia University who, at the time he conducted these studies, was a postgraduate student at the University of Michigan.39... 

Drevets WC, Krishnan KR. Neuroimaging studies of mood disorders in Neurobiology of Mental Illness (Charney DS, Nestler EJ, Bunney BS, Eds) Oxford University Press, New York 1999, pp 394-418... 

Heckers, S. Neuroimaging studies of the hippocampus in schizophrenia. Hippocampus 11 520-528, 2001. 

Soares, J. C. and Mann, J. J. The anatomy of mood disorders — review of structural neuroimaging studies. Biol. Psych. 41 86-106,1997. 

Functional neuroimaging studies suggest that frontal and occipital brain areas are integral to the anxiety response. Patients with panic disorder may have abnormal activation of the parahippocampal region and prefrontal cortex at rest. Panic anxiety is associated with activation of brain stem and basal ganglia regions. GAD patients have an abnormal increase in cortical... 

Some functional neuroimaging studies have examined the effects of scopolamine in cognitive tasks. Although scopolamine inhibits increases in cerebral blood flow to somatosensory stimulation, it does not inhibit the neural response (Ogawa et al. 1994). Thus, cholinergic systems may be involved in coordination of cerebral blood flow increases to neural activation. Subjects performing an attentional auditory discrimination... 

Glucocorticoid receptors are present in a high density in the amygdala and neuroimaging studies have shown that the amygdala is the only structure in which the regional blood flow and glucose metabolism consistently correlate positively with the severity of depression. This... 

Neuroimaging studies showing decreased hippocampal volumes have been described in adults with peri-... 

Preliminary Results of Neuroimaging Studies in Children and Adolescents with Depression... 

Table 10.1 summarizes the results of available pediatric neuroimaging studies in depressed patients. Given the limited amount of available data, published papers and professional presentations are reviewed. Two of the eight studies included seven or fewer depressed subjects, and two had no normal control comparisons. Results from the three largest-scale studies suggest that there are some neuroanatomical correlates of depression that may be evident across the life cycle (e.g., frontal lobe and amygdala volume changes), and others... 

TABLE 10.1. Neuroimaging Studies of Children and Adolescents with Major Depression... 

Drevets, W.C. (2000) Neuroimaging studies of mood disorders. Biol Psychiatry 48 813-829. 

Functional neuroimaging studies provide strong evidence for dysfunction of the cortical-striatal-thalamocortical (CSTC) circuitry. Symptoms of OCD are associated with increased activity in orbitofrontal cortex in neutral state (Swedo et ah, 1989b Baxter, 1994 Saxena et ah, 1998). Increased activity was also noted in some of these studies in anterior cingulate gyrus, caudate nucleus, and thalamus. Horwitz et al. (1991) found that the pattern of intercorrelations between various brain regions in patients with OCD differed from that of controls. 

Baxter, L.R., Jr. (1992) Neuroimaging studies of obsessive compulsive disorder. Psychiatr Clin North Am 15 871-884. 

There have been recent advances in the understanding in brain structure and function of some childhood psychiatric disorders however, no controlled neuroimaging studies involving aggressive childhood disorders and conduct disorders have been published (Peterson, 1995). Despite the fact that ADHD and conduct disorders are commonly comorbid, existent imaging studies of ADHD are not informative, because typically these studies have excluded youths with conduct disorder. 

Ethanol-related cognitive deficits in the absence of Wernicke s encephalopathy also improve with extended abstinence. Most functional neuroimaging studies of abstinent alcoholics have shown decreases in both cerebral glucose metabolism and blood flow, with the decreases being greatest in the frontal lobes (Netrakom et ah, 1999). 

Hendren, R.L., DeBacker, I., and Pandina, G. (2000) Review of neuroimaging studies of child and adolescent psychiatric disorders from the past ten years. / Am Acad Child Adolesc Psychiatry 39 815-828. 

---