Depression is mental disorder characterized by impaired overall functioning as well as diminished cognitive performance. Its cause is associated with an imbalance of neurotransmitter functioning in...Show moreDepression is mental disorder characterized by impaired overall functioning as well as diminished cognitive performance. Its cause is associated with an imbalance of neurotransmitter functioning in affected individuals. Recent studies have demonstrated the ability of L-tyrosine, a natural amino-acid and precursor of the neurotransmitter dopamine, to increase dopamine levels within the brain and subsequently benefit different cognitive functions. Additionally, another field of research has repeatedly shown that exposure to novel stimuli can enhance memory performance in both animals and humans. In our study we investigated whether the intake of tyrosine (administered in a double-blind, betweensubjects design) enhances recall and recognition performance following the exposure to an either novel or familiar virtual reality environment (within-subjects design) in healthy participants. We expected tyrosine and the novelty exposure to result in improved cognitive performance. Furthermore, we hypothesized tyrosine to even out the assumed negative impact of increasing severity of depressive symptoms on the recall and recognition scores. Our sample consisted of 30 individuals aged 18 to 30. The study involved a total of five sessions including three laboratory and two online sessions. The first session included the familiarization to the VR environment as well as the assessment of current depressive symptoms with the patient health questionnaire. The other two laboratory sessions entailed the treatment administration, VR environment exploration as well as immediate memory assessments, while the online sessions consisted of delayed memory assessments. To examine the effects of treatment, novelty, and depressive symptoms on memory performance, our data was analysed with repeated measures analyses of variance. Contrary to our expectations we did not find significant effects of novelty or the tyrosine supplement on recall or recognition scores. While heightened symptoms of depression negatively impacted the cognitive performance in our sample, tyrosine did not have a mitigating effect on the different severity of symptoms. Future research is advised to explore methodological adjustments by making use of more immersive VR methods, alternative dosages of tyrosine, and include clinical samples to better understand these factors' potential impact on memory.Show less
