{"id":"5f795ff6-18a1-5534-af2d-37381dcbde75","stable_key":"63ce713e-6aea-59f6-9896-ca30e010b2ce:l-tyrosine-older-performance","predicate":"reduces","statement":"Load-dependent working-memory performance declined at higher tyrosine doses, particularly in older adults with larger plasma responses.","claim_class":"observational","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"c11b6bbd-e970-5a85-a3a6-e65b4f7d1ad4","mechanism_event_label":"More precursor was not better in this experiment.","subject":{"id":"bcfef85f-831d-5439-ba51-1aef4b090441","slug":"l-tyrosine","display_name":"L-Tyrosine","entity_type_key":"small_molecule"},"object":{"id":"2e1b7048-07d9-51ed-9165-94b17609bd6e","slug":"older-human-load-dependent-working-memory","display_name":"Older-adult load-dependent working memory after tyrosine","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"c11b6bbd-e970-5a85-a3a6-e65b4f7d1ad4","stable_key":"63ce713e-6aea-59f6-9896-ca30e010b2ce:l-tyrosine-older-performance-event","event_type":"observed_relationship","label":"More precursor was not better in this experiment.","description":"Load-dependent working-memory performance declined at higher tyrosine doses, particularly in older adults with larger plasma responses.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"bcfef85f-831d-5439-ba51-1aef4b090441","slug":"l-tyrosine","display_name":"L-Tyrosine","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"2e1b7048-07d9-51ed-9165-94b17609bd6e","slug":"older-human-load-dependent-working-memory","display_name":"Older-adult load-dependent working memory after tyrosine","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary abstract","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Same acute 17-person dose-ranging crossover, with N-back testing at 90 minutes.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Small experimental study; it does not establish a general toxicity threshold or contradict a different cold-stress task.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"L-Tyrosine collection; species, compartment, exposure, co-substrates and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"l-tyrosine","display_name":"L-Tyrosine","entity_type_key":"small_molecule"}},{"dimension":"plain_language","value_text":"More precursor was not better in this experiment.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Dose-Dependent Effects of Oral Tyrosine Administration on Plasma Tyrosine Levels and Cognition in Aging. · 2017 · https://pubmed.ncbi.nlm.nih.gov/29168741/ · DOI 10.3390/nu9121279","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"2b17615d-730d-5154-aee2-81c6e9685225","evidence_kind":"source_excerpt","locator":"Lines 412-418","start_line":412,"end_line":418,"excerpt":"## l-tyrosine-older-performance\nMore precursor was not better in this experiment.\nLoad-dependent working-memory performance declined at higher tyrosine doses, particularly in older adults with larger plasma responses.\nModel: Same acute 17-person dose-ranging crossover, with N-back testing at 90 minutes.\nLimitations: Small experimental study; it does not establish a general toxicity threshold or contradict a different cold-stress task.\nEvidence access: Primary abstract\nDose-Dependent Effects of Oral Tyrosine Administration on Plasma Tyrosine Levels and Cognition in Aging. · 2017 · https://pubmed.ncbi.nlm.nih.gov/29168741/ · DOI 10.3390/nu9121279","model_system":"Same acute 17-person dose-ranging crossover, with N-back testing at 90 minutes.","directness":"reported_statement","verification_status":"source_derived_draft","notes":"Original curation paraphrase; evidence access and experimental limitations specified.","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"12917df2-c6e0-5b61-850f-dbff6d4b4d30","stable_key":"import-63ce713e-6aea-59f6-9896-ca30e010b2ce","title":"L-Tyrosine: catecholamines, thyroid chemistry, pigment, metabolism and cross-nutrient mechanisms (2026-09-19)","document_type":"imported_text","citation_label":"AI-assisted research curation; primary references, access levels and experimental limitations individually identified. 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