Effects of Amphetamine on Sensorimotor Gating and Neurocognition in Antipsychotic-Medicated Schizophrenia Patients

Neuropsychopharmacology. 2018 Mar;43(4):708-717. doi: 10.1038/npp.2017.285. Epub 2017 Nov 20.

Abstract

Prepulse inhibition (PPI) of startle is being explored both as an indicator of target engagement for, and a biomarker predicting the sensitivity to, procognitive effects of drugs. We now report the effects of the pro-attentional drug, d-amphetamine, on PPI and neurocognition in antipsychotic-medicated schizophrenia patients and healthy subjects (HS) who were also tested in a targeted cognitive training (TCT) module. 44 HS and 38 schizophrenia patients completed a double-blind, placebo-controlled crossover study of the effects of a single dose of amphetamine (10 mg po) on PPI and MATRICS Consensus Cognitive Battery (MCCB) performance; TCT results were previously reported from 60 of these subjects. Moderators predicting AMPH sensitivity were assessed, including the rs4680 single-nucleotide polymorphism for catechol-O-methyltransferase (COMT). After placebo, patients exhibited PPI deficits with 60 ms prepulse intervals; these deficits were 'rescued' by amphetamine. The magnitude of amphetamine-enhanced PPI was greater in patients than in HS (p<0.032), and was associated with positive symptoms (p<0.007), antipsychotic load (p<0.015), hedonic effects of AMPH (p<0.003), and with the presence of at least one methionine allele in rs4680 (p<0.008). No significant effects of amphetamine on MCCB performance were detected in either group, though pro-attentional effects of amphetamine in patients were associated with greater amphetamine-enhanced TCT learning. Amphetamine acutely 'normalized' PPI in antipsychotic-medicated schizophrenia patients; no concurrent acute neurocognitive changes were detected by the MCCB. Findings suggest that in the context of appropriate antipsychotic medication, a low dose of amphetamine enhances brain processes associated with higher function in schizophrenia patients, without accompanying changes in MCCB performance.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Amphetamine / pharmacology
  • Amphetamine / therapeutic use*
  • Antipsychotic Agents / pharmacology
  • Antipsychotic Agents / therapeutic use*
  • Cognition / drug effects*
  • Cognition / physiology
  • Female
  • Humans
  • Male
  • Mental Status and Dementia Tests*
  • Middle Aged
  • Neuropsychological Tests
  • Reflex, Startle / drug effects
  • Reflex, Startle / physiology
  • Schizophrenia / drug therapy*
  • Schizophrenia / physiopathology
  • Sensory Gating / drug effects*
  • Sensory Gating / physiology
  • Young Adult

Substances

  • Antipsychotic Agents
  • Amphetamine