Selegiline for Alzheimer's disease

Alzheimer's disease is the most common cause of dementia in older people accounting for some 60% of cases with late-onset cognitive deterioration. It is now thought that several neurotransmitter dysfunctions are involved from an early stage in the pathogenesis of Alzheimer's disease-associated cognitive decline. The efficacy of selegiline for symptoms of Alzheimer's disease remains controversial and is reflected by its low rate of prescription and the lack of approval by several regulatory authorities in Europe and elsewhere. Reasons for this uncertainty involve the modest overall effects observed in some trials, the lack of benefit observed in several trials, the use of cross-over designs which harbour methodological problems in a disease like dementia and the difficulty in interpreting results from trials when a variety of measurement scales are used to assess outcomes.

The objective of this review is to assess whether or not selegiline improves the well-being of patients with Alzheimer's disease.

The Cochrane Dementia and Cognitive Impairment Group Register of Clinical Trials, was searched using the terms 'selegiline', 'l-deprenyl', "eldepryl" and "monamine oxidase inhibitor-B". MEDLINE, PsycLIT and EMBASE electronic databases were searched with the above terms in addition to using the group strategy (see group details) to limit the searches to randomised controlled trials.

All unconfounded, double-blind, randomised controlled trials in which treatment with selegiline was administered for more than a day and compared to placebo in patients with dementia.

Data were extracted independently by the reviewers (JSB & LF), pooled where appropriate and possible, and the weighted or standardised mean differences (95%CI) estimated. Where possible, intention-to-treat data were used but usually the meta analyses were restricted to completers' data (data on people who completed the study).

There are 15 included trials. All trials examined the cognitive effects of selegiline, and in addition, 12 trials examined the behavioural and mood effects. The results of 8 trials suggested some beneficial effect of selegiline in the treatment of cognitive deficits and in 3 trials in the treatment of behaviour and mood. The meta-analysis revealed benefits on memory function as evidenced by improvement in the memory tests from several cognitive tests. Pooling the data for all cognitive tests suggested significant benefits in those subjects treated with selegiline as compared to controls. There were benefits in mood and behaviour as demonstrated by measurements on the Brief Psychiatric Rating Scale and the Dementia Mood Assessment Scale. The global rating scales showed no effect of selegiline. Unfortunately, the evidence using standardised global cognitive scales was extremely limited, for both the MMSE and ADAS-cog. A variety of adverse effects were recorded, but very few patients left a trial as a direct result of the intervention.

Although the evidence for a beneficial effect of selegiline on patients with Alzheimer's disease is promising there is not yet enough evidence to recommend its use routinely in practice. The individual patient data review will yield further evidence on the effects of selegiline compared to control as would additional studies evaluating the use of selegiline for the endpoints of standardised cognitive scales, clinician impression of global change, dependency and caregiver quality of life.