Purpose: Antiepileptic drugs (AEDs) are frequently used for their beneficia
l psychoactive effects on affective disorders. We sought to demonstrate a p
sychoactive effect of gabapentin (GBP) when used as add-on AED therapy.
Methods: Forty adult patients with partial epilepsy were studied in a prosp
ective, non-randomized fashion with interviewer-rated and self-rated scales
of mood and anxiety: the Cornell Dysthymia Rating Scale (CDRS), Beck Depre
ssion Inventory (BDI), and Hamilton Depression (Ham-D) and Anxiety (Ham-A)
Scales. After completion of baseline mood and anxiety scales (time 1), 20 o
f the 40 patients were prescribed add-on GBP (treated group). The remaining
20 patients served as a control group. Both groups were similar in age and
sex distribution, Follow-up mood and anxiety scales were performed in all
patients similar to 3 months later (time 2). The average GBP dose at time 2
was 1,615 mg/day. All patients were taking stable doses of one to four AED
s at baseline and throughout the study. Seizure frequency was monitored thr
oughout. Statistical significance was assessed by analysis of variance (ANO
VA) by using a two-factor repeated-measures model.
Results: The GBP-treated group had a significant decrease in CDRS score ove
r time compared with the control group (p = 0.04). No significant differenc
es between the control and the treated groups were found for any of the rem
aining mood scales (BDI, p = 0.58; Ham-D, p = 0.59; Ham-A, p = 0.93). There
was no significant difference or change in seizure frequency between group
Conclusions: GBP treatment is associated with mood improvement as measured
by the CDRS, This improvement was not accounted for by seizure improvement.