Purpose: We evaluated the dose-related impacts of tiagabine (TGB) on c
ognition and mood in a monotherapy study. Methods: Patients were 123 a
dults with uncontrolled partial seizures, each treated with a single c
urrently available antiepileptic drug (AED) for management of clinical
epilepsy. They completed a battery of neuropsychological tests during
an 8-week prospective baseline period and once again at the end of th
e 12-week fixed-dose period (or earlier if they dropped out of the stu
dy). Sixty-six patients were randomized to 6 mg/day TGB and 57 were ra
ndomized to 36 mg/day TGB. Results: Few changes in either abilities or
adjustment and mood were noted when all patients were considered as a
single group. However, analysis of both dose and attainment of TGB mo
notherapy showed that patients receiving TGB monotherapy did best, imp
roving particularly in the areas of adjustment and mood with low-dose
TGB and in the area of abilities with high-dose TGB. Patients who did
not attain monotherapy showed no change except that the high-dose grou
p did not perform as well on measures of mood and adjustment. Baseline
AED and changes in seizure control did not affect the results. Conclu
sions: Patients' attainment of TGB monotherapy was associated with the
ir achievement of positive changes of varying degree on psychological
tests. Failure to attain TGB monotherapy was associated with no change
s on the tests except in patients receiving high-dose TGB where it app
eared that some alterations in mood might have been avoided if a slowe
r titration schedule had been used.