The findings showed effectiveness of saffron on lessening trait anxiety, though the reduction of state anxiety was not significant. Several studies have confirmed effects of saffron on treating depression, however, none of them have specifically focused on anxiety. On the other hand, animals have been the subjects of studies in this field to evaluate anxiolytic of diazepam.
Herron et al. discussed anxiolytic effects of diazepam through GABA receptors on animal subjects [
16]. Taking into account that saffron is traditionally used as anxiolytic medicine and given its effect on lessening anxiety before surgery, the probable cause of such effects are physiologic and biologic effects of the medicine.
Shabanian et al. studied double blind clinical internship over 60 patients at the age range 14 - 48 years and compared anxiolytic effects of diazepam (5 mg in 100 mL water administered 2 hours before surgery) and orange blossom (100 mL administered 2 hours before surgery). Anxiety level was measured using STAI and the results confirmed reduced state anxiety after administration [
17]. In Banaiyan et al. research the mean of state and trait anxiety was reduced in diazepam group. In our study, the mean of state anxiety in diazepam group was unchanged, but the mean of trait anxiety had increased. These differences may be the result of time devoted to fill out the questionnaire after the intervention and the type of surgery and the study population. In Shabanian study, questionnaire was filled out two hours after oral administration of diazepam [
17]. Previous studies showed that the peak effect of oral diazepam is 1 - 2 hours after drug administration [
18]. But, in our study according to the anesthesiologist that to three hours before surgery drinking water (drug) is permissible for adults, we prescribed for the two groups this drug three hours before surgery, while in Shabanian study 2 hours before the surgery patients had received diazepam [
17].
With an extensive literature review researchers could not find a similar study. Emotional reactions to stressful situations are placed in a wide range of joy and happiness, common excitement, anxiety, anger, frustration and depression. Anxiety is the most common response to stressful stimuli. Anxiety means unpleasant excitement that we all have some degree of it in the form of words, such as concern and fear. But the common human response to failure is active aggression. However, the reverse behaviors, i.e. detachment and isolation are also common. If the stressful situation continues and the person may not succeed in resolving it the depth of the detachment may increase and cause depression [
19].
About 25% - 50% of depressed youth have comorbid anxiety disorders and about 10% - 15% of anxious youth have depression [
20]. Studies on the relationship between depression and anxiety have emphasized one of three different conceptual models: anxiety and depression as a continuum in which anxiety and depressive symptoms overlap and blend together; anxiety and depression as distinct illnesses with clear boundaries; and a mixed anxiety-depressive disorder as a distinct disorder differing from the pure forms of these disorders [
21].
Many studies about the antidepressant effects of saffron has been done on human, that the following can be noted: Shahmansouri et al. in their study showed that short-term treatment with saffron capsules (30 mg daily for six weeks) and fluoxetin (40 mg daily for six weeks) had the same antidepressants effects in patients [
22]. In another study, the effect of saffron (10 mg essence of saffron) was measured as an anti-depression factor and the results were compared with impiramine (30 - 100 mg). The results showed equal efficiency of imipramine and saffron on out-going depression patients (trivial moderate anxiety) and no side effect was observed in the subject [
23]. Our study examined the effect of anti-anxiety of saffron and showed that the mean of trait anxiety had reduced.
Hosseinzade and Noraei studied the anxiolytic and sleep inducing effects of saffron and the compounds (Safranal). Their findings showed that crocins has no anxiolytic effect, although essences of saffron and safranal at high dose (more than 0.15 and 0.35 mg) have anxiolytic effects [
24]. The anti-effects of saffron and diazepam were subject of another study that was planned to examine the anxiolytic effects of crocins on rodents. To this end, the light/dark test was adopted. Crocin at a dose less than that may influence motor activity (50 mg/kg) and diazepam (1.5 mg/kg) both increased the delay to enter the dark compartment an increased the time spent in light chamber among the rat. On the other end, small doses of crocins (15 - 30 mg/kg) made no considerable change in the subjects’ behavior [
25].
Thus, according to these studies, we can say that our research is consistent with other researches in the field of depression. Saffron has crocetin as free compound and trivial amount of pigments anthocyanin, α- and β-carotene, zeaxanthin [
26,
27]. The saffron and crocetin are keen to σ1 (sigma-1) receptor [
28]. Ligands σ1 of the receptor shows anti-cancer, memory/learning/cognition improving, anti-depression, anti-psychosis, anxiolytic and neurons protecting properties. Therefore, the anti-anxiety effects of the dried extract of saffron are probably due to its effect on this receptor. In addition, affinity and connection of saffron, crocins and crocetin to NMDA (N-methyl-D-aspartate) receptor, agonistic effects on GABAA receptor complex of benzodiazepam and opioid receptor have been studied in other works [
29]. Thus, taking into consideration that diazepam induces its effect through GABAA receptor, thus the same path is taken saffron essence powder to induce anxiolytic effects. A limitation in conducting this study was financial limitations for preparing the expensive saffron capsules. For future studies it is recommended to focus separately on different elements of saffron through clinical assessments. It appears that saffron, as a traditional indigenous medical plant is good choice for controlling anxiety before surgery, but further clinical trials are recommended to use saffron as anti-anxiety drug.