A growing body of reports have indicated that free radicals are involved in the etiopathogenesis of some neuropsychiatric disorders. In the present study, we aimed to evaluate whether antioxidant enzymes (superoxide dismutase; SOD, glutathione peroxidase; GSH-Px, and catalase; CAT) activity levels and malondialdehyde (MDA), a product of lipid peroxidation, were associated with social phobia (SP). Eighteen patients diagnosed with SP and 18 healthy controls were enrolled. A clinical evaluation and measurements of MDA, SOD, GSH-Px and CAT were performed. Additionally, all patients were assessed with the Liebowitz Social Anxiety Scale (LSAC). The mean MDA, SOD, GSH-Px and CAT levels in the patient group were significantly higher than those in the control group. There was a positive correlation between LSAC scores and MDA, SOD, GSH-Px and LSAC levels, and between the duration of illness, and MDA, SOD and CAT levels in the patient group. In conclusion, our results suggest that there may be a relationship between increased antioxidant enzyme levels and MDA, and SP.
Free radicals, with an unpaired electron in one of their orbits, are chemical species produced in many different ways, such as activation of phagocytes and the general immune system, lipid peroxidation, electron transport system in mitochondria, ischemia and trauma (Gutteridge, 1995). Free radicals have relatively short half-lives, and thus the determination of their levels is difficult. Therefore, they can be evaluated indirectly by measurement of some antioxidant enzyme levels such as superoxide dismutase (SOD), catalase (CAT) or glutathione peroxidase (GSH-Px), by products of lipid peroxidation such as malondialdehyde (MDA) or by some transition metal levels such as copper, zinc and iron (Leff, 1994). Predominantly superoxide, hydroxyl ion and nitric oxide are generated under physiological conditions during aerobic metabolism (Mahadik and Mukherjee, 1996). A small portion of the free radicals are involved in physiological processes, but the remainder are inactivated by antioxidant enzyme systems (Burton and Ingold, 1989). When free radicals are generated in excessive amounts or the enzymatic and nonenzymatic antioxidant defense systems are inefficient, some chain reactions causing cellular injury or even death of cells are activated (Stadtman, 1992).
Free radical damage has been investigated in the pathophysiology of neuropsychiatric disorders. There are numerous studies indicating that free radical-mediated neuronal dysfunction may be implicated in the pathophysiology of schizophrenia (Mahadik and Mukherjee, 1996). Buckman et al. (1987) reported that patients with chronic schizophrenia had levels of GSH-Px activity similar to those in healthy controls. Increased SOD activity levels in schizophrenia have been reported (Lohr, 1991). In addition, it has been suggested that patients with major depression, especially melancholia, show elevated antioxidant enzyme levels and lipid peroxidation (Bilici et al., 2001).
Another neuropsychiatric disorder in which free radicals might play a role is social phobia (SP). To the best of our knowledge, there has not yet been a study evaluating the association between free radicals and SP. Therefore, in the present study, we hypothesized that oxidative damage and antioxidant enzyme activity levels could be implicated in SP.
