Hippocampal Volume Increased After Cognitive Behavioral Therapy in a Patient With Social Anxiety Disorder: A Case Report

To the Editor: Functional imaging studies have revealed that patients with social anxiety disorder have hyperactivity of the amygdala and surrounding areas, including the hippocampus.¹ However, the number of structural brain imaging studies is limited. Irle et al.² reported that social anxiety disorder patients had reduced amygdala (13%, only male patients) and hippocampus (8%) size and that a smaller right hippocampus is associated with more severe symptoms.

Although some studies detected that the hippocampus/amygdala increase after effective treatments in patients with depression or other anxiety disorders,^3,4 there are no morphological studies in patients with social anxiety disorder.

Here we describe a case in which the hippocampus increased after cognitive-behavioral therapy (CBT).

Case

A 36-year-old woman with an 8-year history of social anxiety disorder received 12 weeks of group CBT.

Scores for the Liebowitz Social Anxiety Scale,^5,6 Social Phobia Scale, and Social Interaction Anxiety Scale^7,8 were obtained before, immediately after, and 3 months after CBT.

We obtained MRI data before and 3 months after CBT using a 1.5-T MRI system (Gyoro Scan Intera; Philips Medical Systems, Best, the Netherlands). The scanning parameters for the three-dimensional T1-weighted turbo field echo sequences were as follows: echo time, 3.9 msec; repetition time, 8.5 msec; flip angle, 15°; 256 × 256 matrices; field of view, 25 cm; voxel size, 1.0 × 1.0 × 1.0 mm; and slice thickness, 1.0 mm.

The hippocampus/amygdala were traced manually according to the method used in a previous study⁹ (Figure 1): an operator blind to subject status traced them twice, and a comparison of the two tracings was made. When the operator used another MRI dataset (N=24), the interrater/intrarater reliability of the hippocampus was 0.89/0.90 and that of the amygdala was 0.80/0.61.

The patient gave written consent, and this study was approved by the Ethics Committee of Nagoya City University.

The volume of the right hippocampus increased from 3417.51 to 3890.50 mm³, and the Liebowitz Social Anxiety Scale scores decreased from 109 to 70 and , Social Interaction Anxiety Scale/Social Phobia Scale scores decreased from 72/43 to 42/19. Clinically, her avoidant behaviors were decreased. The volume of the right amygdala was decreased, and the volume of the left hippocampus/amygdala did not change (Table 1).

Discussion

We described our experience with a patient with social anxiety disorder whose right hippocampal volume increased 3 months after successful CBT.

Previous studies have shown that prolonged stress and a high level of glucocorticoids reduce hippocampus/amygdala volumes and that effective treatment alleviates the situation in major depressive disorders. However, in the case of anxiety disorders, the mechanism of volume reduction is not clear.

Irle et al.² reported that, in female patients with social anxiety disorder, only the hippocampi were smaller than those of healthy control subjects, and the small right hippocampi had an association with symptom severity. Our finding was supported by this study.

However, the reason for the reduction in the right amygdala is unclear and could be becasue of our unskilled tracing technique.

Conclusion

Although larger sample studies are needed, we expect that the right hippocampal volume may have an association with symptom or treatment response in patients with social anxiety disorder.