IQ and mortality

Twenty thousand people living in Sweden who had their IQ measured during childhood have now been followed for more than half a century. Those who scored lower on tests of IQ in childhood experienced higher mortality.

The effect was substantial: in men, a decrease in IQ was roughly equivalent to a 30% increase in risk of death from all causes and, in women, about 15%.

However, without information on lifestyle factors such as smoking, exercise and diet, the underlying mechanisms of this extraordinary finding can’t be investigated any further. Carpal tunnel syndrome, due to compression of the median nerve at the wrist, is common.

Treatment with injections of corticosteroid is effective but the benefit is often shortlived. But a small trial in Taiwan raises the possibility that an injection of dextrose is just as good, if not better.

Improvements in pain and disability were similar in the groups allocated to dextrose and steroid injections at one and three months but, at six months, symptoms were better in the group given dextrose.