Transcranial magnetic stimulation treatment for epilepsy: can it also improve depression and vice versa?

Comorbidity with depression is an important determinant of the quality of life for patients with epilepsy. Antidepressant medications can effectively treat depression in epileptic patients, but drug-drug interactions and epileptogenic effects of these drugs pose therapeutic challenges. The mood-stabilizing effects of antiepileptic medications may not be sufficient to treat depression. Therefore, treatments that alleviate the burden of depression without increasing seizure risk or, better yet, with the possibility of improving seizure control are worth exploring. Neuroimaging techniques, such as functional magnetic resonance imaging, are providing novel insights into the pathophysiology of depression in epilepsy. For example, there appears to be prominent brain prefrontal hypoactivity, which may be sustained by the hyperactivity of the seizure focus. If so, neuromodulatory approaches that suppress epileptic focus hyperactivity and concurrently enhance prefrontal activity may be ideally suited. Indeed, vagus nerve stimulation has been shown to yield simultaneous antiseizure and mood effects. Another neuromodulatory technique, transcranial magnetic stimulation (TMS), can also modulate brain activity, but in a noninvasive, painless, and focal manner. Depending on the stimulation parameters, it is possible to enhance or reduce activity in the targeted brain region. Furthermore, TMS has been shown to be effective in treating depression, and preliminary data suggest that this treatment may also be effective for epilepsy treatment. This article reviews these data and explores further the question of whether depression and epilepsy can be simultaneously treated with TMS for optimal therapeutic impact.