Which anticonvulsant medication may cause weight loss and cognitive issues when used as a mood stabilizer?

Topiramate is known for its potential side effects, which include weight loss and cognitive impairment, particularly when used as a mood stabilizer in certain patient populations. The mechanism behind topiramate's effect on weight is believed to be related to its influence on appetite suppression and increased energy expenditure. Additionally, cognitive effects such as difficulties with concentration, memory problems, and a sensation of being "foggy" can occur, particularly during the initial stages of treatment or when the dosage is escalated.

In contrast, other options like valproate and oxcarbazepine are more commonly associated with weight gain rather than weight loss, making them less likely candidates for causing the symptoms described in the question. Esmolol, being a beta-blocker primarily used for cardiovascular issues, does not fall within the category of anticonvulsants or mood stabilizers, and therefore would not be applicable in this context. This distinction highlights why topiramate is the most appropriate choice among the given options, as it aligns directly with the known side effects of weight loss and cognitive issues when utilized in psychiatric settings.