It is a human study, and it used a relatively low dose theanine - only 250mg daily for 8 weeks. Theanine improved virtually all symptoms including actual symptoms of depression, anxiety, and cognitive function. I wonder what would double that dose have achieved given the study I posted about theanine BOTH reducing serotonin and increasing dopamine.
Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study. - PubMed - NCBI
"...Our study suggests that chronic (8-week) l-theanine administration is safe and has multiple beneficial effects on depressive symptoms, anxiety, sleep disturbance and cognitive impairments in patients with MDD. However, since this is an open-label study, placebo-controlled studies are required to consolidate the effects."
Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study. - PubMed - NCBI
"...Our study suggests that chronic (8-week) l-theanine administration is safe and has multiple beneficial effects on depressive symptoms, anxiety, sleep disturbance and cognitive impairments in patients with MDD. However, since this is an open-label study, placebo-controlled studies are required to consolidate the effects."