Ascorbic acid provides no benefit in CMT 1A

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Ascorbic acid provides no benefit in Charcot—Marie—Tooth disease type 1A?

Reference: The Lancet Neurology, early online oublication, 9 March 2011

Summary by: Hina Radia

According to research published early online in the Lancet Neurology, ascorbic

acid supplementation has no significant effect on neuropathy compared with

placebo, in patients with Charcot—Marie—Tooth disease type 1A (CMT1A).

Previously, ascorbic acid had been shown to reduce the severity of neuropathy in

transgenic mice over-expressing peripheral myelin protein 22 (PMP22), a model of

CMT1A. Subsequently, three 1-year duration studies in humans had shown no

benefit for the use of ascorbic acid; this study was a multicentre 2-year trial

to test the efficacy and tolerability of ascorbic acid in patients with CMT1A.

A total of 271 patients aged 18—70 years with symptomatic CMT1A were enrolled

from 9 centres in Italy and the UK, and were randomly assigned to receive 1•5

g/day oral ascorbic acid or matching placebo for 24 months. The primary outcome

was change in the CMT neuropathy score (CMTNS) at 24 months. Mean CMTNS at

baseline with missing data imputed was 14.7 (SD 4.8) in the ascorbic acid group

and 13.9 (4.2) in the placebo group.

The researchers reported that mean worsening of CMTNS was 0.2 (SD 2.8, 95% CI

& #8722;0.3 to 0.7) in the ascorbic acid group and 0.2 (2.7, & #8722;0.2 to 0.7)

in the placebo group (mean difference 0.0, & #8722;0.6 to 0.7; p=0.93).

Furthermore, 21 serious adverse events occurred in 20 patients, 8 in the

ascorbic acid group and 13 in the placebo group. A total of 15 patients (11%) in

each treatment group discontinued treatment early, of whom 6 in the ascorbic

acid group and 5 in the placebo group discontinued because of oral or

gastrointestinal symptoms.

The researchers conclude that consistent with previous studies which showed that

ascorbic acid did not have any effect on neuropathy in patients with CMT1A, this

study further implies that ascorbic acid provides no benefit in the long term

management of patients with the condition.

A related editorial has discussed the study.