Driving for more than two hours a day negatively affects IQ levels, scientists have warned. 

科学家警告称，每日驾驶时间超过2小时会对智商产生消极影响。

In what might come as unwelcome news for middle-aged commuters, a recent study found that long periods behind the wheel could speed up the effects of age on the brain. 

The researchers said that the results could be explained by the fact that the mind is less active on long car journeys. 

The mammoth project saw more than half a million Britons aged 37-73 studied over a period of five years. 

Out of these some 93,000 of them drove more than two or three hours a day. 

Researchers found that not only did this proportion of subjects typically have lower brainpower to begin with but their IQ score declined more rapidly over the course of the study than those who did little or no driving.

Previous studies have found that long periods of inactivity have a detrimental affect on brainpower and Dr Bakrania's research shows similar results for those who watched more than two hours of television a day. 

But the study also found using computers actually boosted people's cognitive stills, leading the scientist to propose another potential factor for driving's negative effects. 

'Driving causes stresses and fatigue, with studies showing the links between them and cognitive decline.'