The biology of depression in Arab culture

Plasma amino acids, cortisol, prolactin, oestrogen, progesterone, thyroxine, thyrotropin, folate, vitamin B-12, urinary biopterins, and neopterins were measured in 33 male and 30 female patients with DSM-III-R major depression. The results were compared with those obtained in 32 male and 38 female normal controls. Male depressive patients had significantly lower plasma levels of tryptophan, cysteine, thorine, ornithine, tryptophan/large neutral amino acids (LNAA) ratio, folate, vitamin B-12, oestrogen, and thyroid-stimulating hormone levels than normal controls. Male depressive patients, however, had significantly higher plasma levels of methionine and thyroxine than normal controls. Female patients had fewer significant differences with lower plasma levels of histidine, ornithine; glutamine, and tryptophan/LNAA ratio, and higher plasma levels of arginine, cortisol, and prolactin than normal female controls. The results are consistent with those obtained in Western populations and support the notion of a universal biologic substrate for depression.