title: The effects of methylphenidate and propranolol on the interplay between induced-anxiety and working memory.
abstract: Research documents a reciprocal impact of anxiety on working memory (WM), although its strength and direction depend on factors like task difficulty. A better understanding of these factors may generate insights into cognitive mechanisms of action involved in anxiety, culminating into treatment implications. By blocking the physiological effects of anxiety, propranolol might also block anxiety interference on WM. Conversely, by improving task-directed attention, methylphenidate might reduce anxiety, or, alternatively, by improving cognitive efficiency and free up processing resources to compute anxiety.
  
  
  
  To investigate the interplay between induced anxiety and WM, we pharmacologically manipulated either anxiety or cognition, using single doses of 40 mg propranolol (PRO), 20 mg methylphenidate (MPH), or placebo (PLA). In this double-blind parallel-group design study, 60 healthy volunteers (20/drug group) performed a verbal WM task under three loads, 1-, 2- and 3-back, and in two conditions, threat of shock and safety. Startle electromyography (EMG) was used to measure anxiety.
  
  
  
  Findings were twofold: (1) MPH blocked anxiety interference only on the 3-back WM performance, while PRO or PLA had no effects on anxiety-WM interference, and (2) drugs had no effects on anxiety, but, after controlling for baseline anxiety, MPH enhanced anxiety-potentiated startle during the 3-back task.
  
  
  
  These findings support that MPH-related improvement of cognitive efficiency permits anxiety to be processed and expressed. In conclusion, MPH may be a useful tool to investigate the mechanisms of interaction between anxiety and WM, particularly those under catecholaminergic control.
authors: Neurobiology of Fear and Anxiety, National Institute of Mental Health, 15K North Drive, Bldg 15K, MSC 2670, Bethesda, MD, 20892-2670, USA. ernstm@mail.nih.gov.
authors: Monique
authors: M
authors: Ernst
authors: Neurobiology of Fear and Anxiety, National Institute of Mental Health, 15K North Drive, Bldg 15K, MSC 2670, Bethesda, MD, 20892-2670, USA.
authors: Tiffany
authors: T
authors: Lago
authors: Neurobiology of Fear and Anxiety, National Institute of Mental Health, 15K North Drive, Bldg 15K, MSC 2670, Bethesda, MD, 20892-2670, USA.
authors: Andrew
authors: A
authors: Davis
authors: Neurobiology of Fear and Anxiety, National Institute of Mental Health, 15K North Drive, Bldg 15K, MSC 2670, Bethesda, MD, 20892-2670, USA.
authors: Christian
authors: C
authors: Grillon
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000328:Adult; D001007:Anxiety; D001288:Attention / Q000187:drug effects*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D004311:Double-Blind Method; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000187:drug effects*; D008774:Methylphenidate / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D000319:Adrenergic beta-Antagonists; D000697:Central Nervous System Stimulants; D008774:Methylphenidate; D011433:Propranolol
keywords: Catecholamine; Cognition; Dopamine; Fear-potentiated startle; Limited resources theory; Stimulant