MOTONEURONE DISEASE AND AGEING

New methods for estimating numbers of functioning motor units in human muscles have shown that muscle denervation is part of the normal ageing process and that it becomes more striking beyond the age of 60. The similarity of this age to the peak age-incidence of motoneurone disease is not regarded as fortuitous—rather it is argued that the disease is an accelerated form of normal ageing. It is thought that motoneurone ageing is determined genetically, but that secondary factors may influence its course.