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An Exploratory Open Label Study of Adjunctive L-lysine Treatment in Patients With Schizophrenia

This study has been completed.
Stanley Medical Research Institute
Information provided by:
Göteborg University Identifier:
First received: October 15, 2009
Last updated: NA
Last verified: October 2009
History: No changes posted
The objective of the present study was to investigate the possibility of using L-lysine, an amino acid that occurs naturally in food and which interferes with nitric oxide (NO) production, for the treatment of schizophrenia. L-lysine, 6 g/day, was administered to ten patients with schizophrenia as an add-on treatment to conventional antipsychotic treatment. The study was designed as a single-blinded, cross-over study where patients were randomly assigned to initial treatment with either L-lysine or placebo and screened at baseline, after four weeks when treatment was crossed over, and after eight weeks when treatment was terminated. The four-week L-lysine treatment regimen caused a significant increased in blood concentration of the amino acid and was tolerated well. The analysis of outcome measures showed a significant decrease in symptom severity as measured by the Positive and Negative Syndrome Scale (PANSS). Furthermore, the patient's ability to solve the Wisconsin Card Sorting Task (WCST) was significantly improved indicating increased problem solving capacity and cognitive flexibility. Subjective reports from three of the patients also indicated decreased symptom severity and enhanced cognitive functioning. In summary, these findings suggest potential beneficial effects of L-lysine treatment on symptom severity and cognitive deficits in patients with schizophrenia.

Condition Intervention
Schizophrenia Drug: L-lysine

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single Blind (Participant)
Primary Purpose: Treatment
Official Title: An Exploratory Open Label Study of Adjunctive L-lysine Treatment in Patients With Schizophrenia

Resource links provided by NLM:

Further study details as provided by Göteborg University:

Primary Outcome Measures:
  • Psychotic symptoms severity [ Time Frame: Eight weeks ]

Secondary Outcome Measures:
  • Treatment safety assessment [ Time Frame: Eight weeks ]

Enrollment: 10
Study Start Date: September 2007
Study Completion Date: March 2009
Primary Completion Date: September 2008 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: L-lysine Drug: L-lysine
6 g/day for four weeks


Ages Eligible for Study:   23 Years to 56 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • a stable phase of illness
  • a stable dose of antipsychotic medication
  • no other major medical conditions or other psychiatric diagnosis
  • normal admission laboratory tests and vital signs

Exclusion Criteria:

  • substance abuse, apart from smoking
  Contacts and Locations
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Please refer to this study by its identifier: NCT00996242

Sahlgrenska Univeristy Hospital
Gothenburg, Sweden, SE 405 30
Sponsors and Collaborators
Göteborg University
Stanley Medical Research Institute
  More Information

Publications automatically indexed to this study by Identifier (NCT Number):
Responsible Party: Birgitta Rembeck, PhD, The Sahlgrenska University Hospital, Gothenburg, Sweden Identifier: NCT00996242     History of Changes
Other Study ID Numbers: LYSINE1
Study First Received: October 15, 2009
Last Updated: October 15, 2009

Keywords provided by Göteborg University:

Additional relevant MeSH terms:
Schizophrenia Spectrum and Other Psychotic Disorders
Mental Disorders processed this record on July 24, 2017