Several in vitro and in vivo studies indicate that polyphenols can affect neuronal system and processes [3]. It should be kept in mind that the effects of polyphenols in vivo may be different from the effects in vitro, as in vivo rather metabolites of polyphenols are active than original substances. For example, curcumin, a nonflavonoid phenolic compound present in Curcuma longa, known and used in Indian traditional medicine, after administration significantly decreased depression-like behaviour in rats probably through improvement of the BDNF level [69]. Curcumin coadministered with alkaloid piperine inhibited MAO activity and increased serotonin and dopamine level in mice [70]. Sanmukhani et al. [71] provides clinical evidence that curcumin (1000 mg/day) administered for 6 weeks to 60 patients with major depression in randomized and placebo controlled trial may be used as an effective and safe modality for treatment of depressive patients without concurrent suicidal ideation. On the contrary to results of Sanmukhani et al., Bergman et al. [72] did not observe significant differences between the groups of patients with administered curcumin (500 mg) and placebo for 5 weeks in randomized, double-blind, and placebo controlled clinical study, probably due to low daily doses used. However, the patients in the curcumin group demonstrated a trend to a more rapid relief of depressive symptoms in comparison to those in the placebo group.

The prevalence of psychiatric disorders permanently increases. Polyphenolic compounds can be involved in modulation of mental health including brain plasticity, behaviour, mood, depression, and cognition. In addition to their antioxidant ability other biomodulating properties have been observed. In the pathogenesis of depression disturbance in neurotransmitters, increased inflammatory processes, defects in neurogenesis and synaptic plasticity, mitochondrial dysfunction, and redox imbalance are observed. Ginkgo biloba, green tea, and Quercus robur extracts and curcumin can affect neuronal system in depressive patients. ADHD patients treated with antipsychotic drugs, especially stimulants, report significant adverse effects; therefore, an alternative treatment is searched for. An extract from Ginkgo biloba and from Pinus pinaster bark, Pycnogenol, could become promising complementary supplements in ADHD treatment. Schizophrenia is a devastating mental disorder, with oxidative stress involved in its pathophysiology. The direct interference of polyphenols with schizophrenia pathophysiology has not been reported yet. However, increased oxidative stress caused by haloperidol was inhibited ex vivo by different polyphenols. Curcumin, extract from green tea and from Ginkgo biloba, may have benefits on serious side effects associated with administration of neuroleptics to patients suffering from schizophrenia. Polyphenols in the diet have the potential to become medicaments in the field of mental health after a thorough study of their mechanism of action.

what antioxidants doWork as a natural pesticide for nutrient-rich fruits and vegetablesShorten attention spanActivate neurotransmittersFight off free radicals that destroy brain cells

According to the National Institute of Health Curriculum Supplement Series book, most scientists believe that changes in neurotransmitters can cause mental illnesses.

Select what antioxidants doWork as a natural pesticide for nutrient-rich fruits and vegetablesShorten attention spanActivate neurotransmittersFight off free radicals that destroy brain cells

What are potential short-term effects of THC on the brain?