An Exploratory Open Label Study of Adjunctive L-lysine Treatment in Patients With Schizophrenia
Status:
Completed
Trial end date:
2009-03-01
Target enrollment:
Participant gender:
Summary
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.