D-cycloserine for Alzheimer's disease (Cochrane Review)

A substantive amendment to this systematic review was last made on 17 January 2002. Cochrane reviews are regularly checked and updated if necessary.

Background: Evidence supports a role for the NMDA receptors in learning and memory. These can be modulated by the antibiotic D-cycloserine in such a way that the effect of the excitatory transmitter substance glutamate is enhanced. A study on healthy subjects pretreated with scopolamine to mimic Alzheimer's disease showed a positive effect of D-cycloserine at low doses.

Objectives: To assess the efficacy and safety of D-cycloserine in patients with Alzheimer's disease.

Search strategy: The trials were identified from a search of the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group on 14 June 2001 using the terms: cycloserine, D-cycloserine, Alzheimer*.

Selection criteria: Randomized, double-blinded and unconfounded trials comparing D-cycloserine with a control treatment.

Data collection and analysis: Two larger and two smaller randomized controlled trials were identified. The clinical global impression scale was used in all studies and was a primary outcome measure.

Main results: It was not possible to extract the results from the first phases of the two crossover studies and therefore the meta-analyses are based on the two parallel group 6-month studies. There was no indication of a positive effect favouring D-cycloserine for the numbers showing improvement at 6 months as assessed by the Clinical Global Impression for any dose. The number of withdrawals for any reason before end of treatment at 6 months was significantly in favour of placebo (fewer withdrawals) compared with D-cycloserine for dose levels of 30 mg/day (OR 2.94, 95% CI 1.52, 5.70) and 100 mg/day (OR 3.23, 95% CI 1.67, 6.25). There was no significant difference between treatment, (2, 10, 30, 100, or 200 mg/day) and placebo for the number of withdrawals due to adverse events by six months.

Reviewers' conclusions: The lack of a positive effect of D-cycloserine on cognitive outcomes in controlled clinical trials with statistical power high enough to detect a clinically meaningful effect means that D-cycloserine has no place in the treatment of patients with Alzheimer's disease.

Citation: Laake K, Oeksengaard AR. D-cycloserine for Alzheimer's disease (Cochrane Review). In: The Cochrane Library, Issue 3, 2003. Oxford: Update Software.

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This is an abstract of a regularly updated, systematic review prepared and maintained by the Cochrane Collaboration. The full text of the review is available in The Cochrane Library (ISSN 1464-780X).

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