Brain metabolism under resting conditions assessed with FDG-PET

[¹⁸F]Deoxyglucose positron emission tomography (FDG-PET) can be used to assess baseline brain metabolism under resting conditions. The first study using FDG-PET in BPD was conducted by Goyer and coworkers (1994). Their investigation comprised 17 patients with DSM III-R personality disorders, six of which (four women and two men) were clinically diagnosed with BPD. However, the average score on the diagnostic interview for borderlines (DIB; Zanarini et al., 1989) in the BPD group was only 3.7, which is only about half of the usual cut-off score of 7. Thus, the results have to be interpreted with caution. In the group of six BPD patients, the authors found decreased metabolism in upper bilateral prefrontal cortex as well as increased metabolism in lower left and right prefrontal areas. Since the spatial resolution of the analysis is low and no Brodmann areas are presented, it appears difficult to specify which parts of prefrontal cortex are dysfunctional, e.g. if the regions shown to have elevated and decreased metabolism comprise parts of anterior cingulate cortex (ACC). A second functional brain imaging study employing FDG-PET was conducted in a series of 10 patients (eight women and two men) with BPD and a DIB score of 7 or higher (De la Fuente et al., 1997). This investigation revealed decreased metabolism in premotor areas and dorsolateral prefrontal cortex, parts of the ACC (BA 25), as well as thalamic, caudate and lenticular nuclei, in BPD patients as compared to controls. Soloff et al. (2003), in a series of 13 impulsive BPD subjects, found decreased metabolism only in the medial orbital frontal cortex bilaterally (BA 9, 10 and 11).

We studied brain metabolism at baseline in 12 medication-free female patients with BPD without current substance abuse or major depression and 12 healthy female controls by FDG-PET and statistical parametric mapping (Juengling et al., 2003). This study revealed glucose metabolism to be significantly increased in patients with BPD compared to controls in the anterior cingulate, the superior frontal gyrus bilaterally, the right inferior frontal gyrus and the opercular part of the right precentral gyrus. Decreased metabolism was found in the left cuneus as well as in the left hippocampus. We could not replicate the findings of De la Fuente and Soloff who found prefrontal hypometabolism. Divergent findings may be due to differences in gender homogeneity as well as the inclusion of different subtypes of BPD (impulsive versus anxious borderline patients).

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