Neurobiology of Depressive Symptoms Predictive of Stroke Among Japanese
To the Editor:
Ohira et al1 find that depressive symptoms predict risk of stroke, specifically ischemic stroke among Japanese. Neurobiological features are suggested by reports linking vasospasm and dysregulation of coping behavior, cortical silent periods, and mood with dopamine abnormalities lateralized to the right hemisphere. This hypothesis is supported by optimal response organization and working memory at intermediate dopamine tone in a mediofrontostriatal activation system, and deactivation of the right hemisphere, a state marker of depression, which promotes dominance of the left hemisphere associated with cardiac dysrhythmia and vasoconstriction. These findings are supported by an exaggerated cerebral cortical response and exaggerated asymmetry to mental stress in patients with coronary artery disease.2
Therefore, prevention of ischemic stroke through intervention on depression3 may be attained by cognitive-behavioral and/or pharmacotherapeutic intervention that balances asymmetric brain functions and alleviates depressive symptoms, such that patients rely less on inappropriate emotion-focused coping strategies.2
Ohira T, Hiroyasu I, Satoh S, Sankai T, Tanigawa T, Ogawa Y, Imano H, Sato S, Kitamura A, Shimamoto T. Prospective study of depressive symptoms and risk of stroke among Japanese. Stroke. 2001; 32: 903–908.
Simons LA. Is depression a risk factor for ischemic stroke? Stroke. 2001; 32: 907–908.Editorial comment.
Dr Friedman raises the hypothesis that the right hemisphere is more likely to be affected in depression-related ischemic strokes, pointing out that the intervention on depression balancing asymmetric brain functions may be useful for the prevention of ischemic stroke.
We explored whether the lesions of incident ischemic strokes among persons with higher depression scores at baseline were more likely to be localized to the right hemisphere compared with those among persons with lower depression scores. The findings of CT scan or MRI were available for 37 of the 39 ischemic strokes.1 The proportions of ischemic strokes with the lesion in the right hemisphere were 50% (4/8) in cases in the low tertile (≤30) of the Zung Self-Rating Depression Scale, 56% (5/9) in the medium tertile (31–34), and 60% (12/20) in the high tertile (≥35). This trend was far from statistically significance (P=0.63), in part due to a small number of cases. Therefore, our result neither supports nor negates Dr Friedman’s hypothesis. Further follow-up of our cohort or the exploration of the data from larger follow-up studies is necessary.
Ohira T, Iso H, Satoh S, Sankai T, Tanigawa T, Ogawa Y, Imano H, Sato S, Kitamura A, Shimamoto T. Prospective study of depressive symptoms and risk of stroke among Japanese. Stroke. 2001; 32: 903–908.