Results

Weight changes
Patients have received topiramate for between 6 months and one year by the time of writing this report. Six of them are still continuing the treatment. The weight changes are shown in Figure 1 and Table 1. All post-treatment levels and the pre-treatment levels from the previous two years, where available, are shown in Figure 1. At 3 and 6 months, 12 patients lost a mean of 4.96 and 7.75 kg respectively. The nine patients who completed 12 months treatment showed a weight loss of 10.2 and 9.61 kg at the 9th and 12th month respectively. All these changes are significant at p < = 0.005.
Figure 1  Weight changes in the patients described in the study. The day of treatment is on the x-axis. The day when topiramate was started is day 0 and weight measurements before that point are supplied where available. Each patient's number as referred to in the text is given on the right of the figure.

Side effects
One patient (N 5) noticed thinning of her hair and stopped the topiramate after six months. This side effect is known with other mood-stabilizers such as valproate. If true, it is likely to be quite rare, as it has not been mentioned in previous papers, or listed as a side effect. We submitted a report for a suspected adverse drug reaction to the Committee on Safety of Medicines in the UK. One patient (N 10) complained of paraesthesia, sore tongue and bad taste in her mouth and stopped topiramate during an earlier treatment (on Figure 1 this coincides with an earlier short period of weight loss). She restarted it 7 months later (as her weight had increased again by 5.5 kg). This time the medication was titrated more slowly by 25 mg/day every two weeks and she did not experience these side effects. This second start of treatment with topiramate is taken as day 0 for the purposes of this report, as it was of a longer duration and is still on-going. One patient (N 2) complained of paraesthesia, later developed unsteadiness of gait and finally severe Parkinsonism, therefore most of her medications, including topiramate were stopped. This patient was taking a number of psychotropic and cardiovascular drugs (a total of nine!), so we do not know whether topiramate was to blame for her neurological signs, especially as she had been taking this drug for over one year already. She recovered completely around 4 months later and no cause for her condition was identified, despite numerous investigations and consultations. We cannot exclude the possibility that topiramate was at least partially responsible, alone, or in combination with several other drugs, therefore we report this event here. Two patients complained of memory and concentration problems but preferred to continue with the medication despite this. These side effects are also well recognised. One patient did not like the appetite suppressing effect of topiramate and stopped it after only one month, so his data is not analysed in the study.

Clinical changes
We do not perform regular formal ratings of the mood of our patients. However we regularly record their condition and changes since the previous appointment. Clear improvement of the course of illness was noticed only in one patient (N 3), while eight patients continued to display a similar pattern of illness, as they had done before the treatment. None of them was judged to have deteriorated. The patients in remission remained well. One patient (N 12) whose carbamazepine was changed to topiramate developed a manic episode, therefore we stopped his topiramate after 6 months and asked him to resume carbamazepine.