A great many people who have long commutes to and from work loathe the amount of time they spend in their car. The traffic, the monotony, the stormy days when you white-knuckle both trips can be draining. Well, it turns out that these drives a bit more than frustrating; they may actually drain people of their intelligence. 
Researchers in Britain found that regularly driving more than 2 hours a day steadily lowers IQ, especially in middle-aged adults.
How and why?
The physically- and mentally-sedentary process of sitting behind the wheel for long stretches can cause stress and fatigue, both of which are factors in brain decline, according to the authors of the study.
Researcher Rosa Sancho said:
“Staying mentally and physically active helps keep our brains healthy, so it is not surprising.”
Kishan Bakrania, a medical epidemiologist at Leicester University in Britain, said:
“We know that regularly driving for more than 2 to 3 hours a day is bad for your heart. This research suggests it is bad for your brain, too, perhaps because your mind less active in those hours.”
Studying the Link Between Driving and Brain Decline
For the study, researchers looked at the lifestyles of more than 500,000 Britons ages 37 to 73 for 5 years. 
“Cognitive decline is measurable over 5 years because it can happen fast in middle-aged and older people. This is associated with lifestyle factors such as smoking and bad diet — and now with time spent driving.”
During that time, the participants took intelligence and memory tests.
Two key results arose from the study:
- 93,000 people who drove for more than 2 to 3 hours a day generally had lower brainpower before the launch of the study.
- During the study period, the participants’ brainpower continued to decline, and did so at a faster rate than for people who spent minimal time on the road.
In his earlier research, Bakrania found that TV viewing affected the brain in much the same way driving for too long affected the brain. People who typically watched 2 to 3 hours of TV a day had lower brainpower at the start of the study, and their brainpower declined throughout the research.
The opposite was true of those who used computers. Whether it was for work or play, using a computer up to 2 or 3 hours a day increased brain function.
“Cognitive skills were boosted in people who used computers up to two to three hours a day. When watching TV, your brain is less active but using a computer is stimulating.”
Bakrania theorizes there are other factors at play in IQ decline during driving besides inactivity. He explained:
“Driving causes stress and fatigue, with studies showing the links between them and cognitive decline.” 
The scientists said people who frequently spend more than 2 hours behind the wheel should minimize their driving time and take up mentally-stimulating activities.
 New York Post
 The Sunday Times