Abstracts

RATIONALE: Glutamic acid decarboxylase (GAD) is involved in the synthesis of gamma-aminobutyric acid (GABA). Inhibition of GABA-synthesis by antibodies against GAD (GAD-Abs) might decrease GABA concentration in the brain and increase the susceptibility of seizures. GAD-Abs are previously reported to occur in association with type 1 diabetes, Stiff man syndrome, cerebellar ataxia and in a few cases with epilepsy. This study aimed to clarify the prevalence of GAD-Abs in a large, non-selected group of patients with epilepsy. METHODS:All patients with epilepsy attending the Outpatient Department of Neurology at Oulu University Hospital over the period of 1997-1999 (n=1386) were asked to participate in this study. Serum samples were obtained from 995 patients with epilepsy after their informed consent. Data regarding the history of antiepileptic medication, duration of epilepsy, type of epileptic syndrome, seizure frequency, coexisting diseases and the results of previous neuroimaging studies were collected by interviewing the patients and by reviewing the patients charts. RESULTS:_GAD-Abs were found in 18 patients, who all had localization related epilepsy. Five of them had high titers of GAD-Abs. Seven of the 18 patients had one or more coexisting autoimmune disease, such as hypothyreosis, multiple sclerosis, systemic lupus erythematosus, autoimmune trombosytopenic purpura, diabetes, sarcoidosis and Sj gren s syndrome. Furthermore, eight of these patients had psychiatric problems, mainly depression and psychosis. CONCLUSIONS:_Our data suggest that GAD autoimmunity may be associated with localization related epilepsy with psychiatric problems. However, further studies are needed to confirm this finding.