Why older people are more likely to fall

Scientists from McGill University have found a possible explanation for why people find it harder to keep their balance as they age and fall more often.

The new study shows that aging reduces the activity of an important type of neuron in the cerebellum - Purkinje cells. And this is directly linked to a decline in movement coordination.

The team tested this on mice of different ages: from young adults (about 2 months old) to "seniors" (about 18-24 months old). The older mice performed worse on coordination tasks - for example, they were quicker off a rotating rod (rotarod test) and worse on a narrow surface.

Next, the researchers measured the electrical activity of Purkinje cells and saw that in old animals these cells send impulses less often (reduced frequency of "spontaneous" activity). Then the scientists made a key test of causality: using the genetic tool DREADD they artificially changed the excitability of neurons.

The result was straightforward:

• if in young mice "slowed down" Purkinje cells to the level of old mice - they began to be worse at rotarod;

• if in old mice, on the contrary, increased the activity of these neurons - their coordination improved, and they stayed longer in the test.

A similar effect was seen in another task: after training to pull a metre rope for the sake of a reward, old mice made more mistakes, but when "spurring" the activity of Purkinje cells errors became less.

The authors note that the work could be important for the prevention of falls and in general for understanding "motor ageing". But this is still about results on animals: there is still a long way to go before drugs or procedures for people, further research is needed.