Omega-3 fatty acids decreased in social anxiety disorder patients

Researchers have found evidence to suggest that the "phospholipid hypothesis" already attributed to depression may also be relevant to social anxiety disorder.

Pnina Green (Rabin Medical Center, Petah Tiqwa, Israel) and colleagues report an altered red blood cell polyunsaturated fatty acid (PUFA) composition in patients with social anxiety disorder, with the degree of n-3 PUFA deficiency linked to the severity of the disorder.

"The robust relationship between low erythrocyte n-3 PUFA concentrations and social anxiety disorder justifies exploration of relevant neuropathophysiological mechanisms," they say.

The researchers looked at the potential role of PUFA composition of phospholipids in 27 untreated, nondepressed patients with social anxiety disorder and 22 mentally healthy controls.

Severity of social anxiety disorder was determined using the Liebowitz Social Anxiety Scale (LSAS), while erythrocyte PUFA concentrations were measured by gas-liquid chromatography.

The results, published in the journal European Neuropsychopharmacology, showed that most concentrations of n-3 PUFAs were lower in the patients than in controls.

The concentrations of a-linoleic acid (18 : 3n-3), the main precursor of essential fatty acids, were 32% lower, and 20 : 3n-3 concentrations 34% lower. The concentration of eicosapentaenoic acid (20 : 5n-3) was 36% lower, and docosahexaenoic acid (DHA; 22 : 6n-3) concentrations were 22% lower.

No other levels of fatty acids were significantly different in the patients, compared with controls.

The researchers note that levels of n-3 PUFAs correlated significantly with LSAS scores. 20 : 3n-3 scores strongly predicted LSAS score, while an inverse correlation was found between the erythrocyte DHA level and LSAS score.

These findings, in addition to the between-group difference in n-3 PUFA concentration, "all point towards a robust relationship between n-3 PUFA deficiency and social anxiety disorder," say Green and team.

"It is possible that the decreased tissue DHA, as reflected by the red blood cell composition, also reflects the DHA status in the brain and plays an etiologic role in the clinical manifestations of social anxiety disorder," they explain.

"Alternatively, the social anxiety disorder process itself may influence the fatty acid composition."

The researchers conclude that the phospholipid hypothesis may apply to social anxiety disorder, "thereby opening new therapeutic options."

Eur Neuropsychopharmacol 2006; 16: 107-113