The commonly used psychiatric medicine lithium may not work in the treatment of the rare motor neuron degeneration disease amyotrophic lateral sclerosis (ALS), says a new study.

Researchers at the University Of Torino, Italy have found that lithium, when given to ALS patients in doses, was not of much use.

"Lithium could have an effect on one of the mechanisms supposedly related to the motor neuron degeneration in ALS, the accumulation of pathological proteins in the neuron," Dr. Adriano Chio, an associate professor of neurology at the University of Torino, Italy, who led the new study.

He, however, added that subsequent research has not confirmed this effect. The study conducted in 71 patients with ALS found drop-out rate, at 68 percent, was two times higher than the drop-out rate reported by previous trials, says Chio in the findings that has been published in the August 17 issue of medical magazine Neurology.

A previous study involving 171 people with ALS was stopped midway in November 2009, because of high dropout rates from death and side effects.

The researchers gave lithium in two different doses to all the participants. Lithium was not well-tolerated by either group. Patients died or lost their autonomy at the same rate in both groups, Chio pointed out.

Lithium was not tolerated even at very small subtherapeutic doses. All the 71 patients reported at least one adverse event, some as serious as heart disturbance, cerebral haemorrhage or deep vein blood clots.

Currently, Chio and his colleagues are conducting two more studies assessing the effect of lithium in ALS. But Chio is not much optimistic about the outcome of the studies.

ALS is a progressive nervous system disorder that causes weakness in muscles, including those controlling breathing and swallowing. Patients with ALS do not survive beyond three years. Only one drug called riluzole is approved for ALS treatment in the United States, so far.

Another Italian study published two years ago had showed that lithium could prolong survival of 16 ALS patients.

Researchers, however, said there are limitations in the latest study. Dr. Carmel Armon of Tufts University said one limitation of the Chio study, which Chio acknowledges, is that it didn't use a true placebo, but rather different doses. Other ongoing studies that are comparing the active drug to placebo may give the definitive answers, in an editorial accompanying the study.