Ethnopharmacological relevance: Previous studies conducted on animals linked consumption of Nigella sativa L. seeds (NS) to decreased anxiety and improved memory. The present study, which was carried out at a boarding school in Bangladesh, was designed to examine probable effect of NS on mood, anxiety and cognition in adolescent human males.
Materials and methods: Forty-eight healthy adolescent human males aged between 14 to 17 years were randomly recruited as volunteers and were randomly split into two groups: A (n=24) and B (n=24). The treatment procedure for group A and B were one capsule of 500 mg placebo and 500 mg NS respectively once daily for four weeks. All the volunteers were assessed for cognition with modified California verbal learning test-II (CVLT-II), mood with Bond-Lader scale and anxiety with State-Trait Anxiety Inventory (STAI) at the beginning and after four weeks of either NS or placebo ingestion.
Results and discussion: No parameter showed statistically significant variation between A and B in measurements in the beginning, but after 4 weeks of one capsule of NS 500 mg intake, there was statistically significant variation of mood within group B but there was not statistically significant variation between group A and B. No significant variation was found in state anxiety within groups and between group A and B but in case of trait anxiety, significant variation was found within group B but not between group A and B. In case of CVLT II, there was significant variation within B in immediate short-term recall at trial 4 and 5 whereas this difference was found only in case of trial 5 between group A and B. Within group B, short term-free recall, long-term free recall and long-term cued recall had statistical difference whereas between group A and B long-term free recall and long-term cued recall had statistical difference. No parameters had significant variation within group A after placebo intake for 4 weeks.
Conclusions: Over the 4 weeks study period, the use of NS as a nutritional supplement been observed to- stabilize mood, decrease anxiety and modulate cognition positively. However, long term study is suggested before using NS extensively.
Keywords: Adolescents; Bond–Lader scale; Clinical Trial; Modified California verbal learning test-II; Nigella sativa L. seeds; State–Trait Anxiety Inventory.
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