Depression in teenagers lowers IQ in adults

Television makes the brain shrink faster

CHICAGO. The fact that people who spend four or more hours a day in front of the telly rarely belong to the intellectual peak can be taken as evident even without evidence from large-scale studies.

What is more controversial is the question of whether the mostly extremely shallow program corrodes the brain or whether it is more due to the passive staring into the screen when cognitive abilities fall by the wayside after many years of watching TV. Of course, there could also be a reverse causation: less intelligent contemporaries might think of nothing better in their free time than killing the time in front of the telly.

A new, as yet unpublished evaluation of the CARDIA * study (Coronary Artery Risk Development in Young Adults) cannot completely rule this out, but it suggests that excessive television consumption is followed by mental and organic brain degradation: Young adults show, who zap through television programs for four or more hours a day for 20 years, in middle age a significantly lower volume of gray matter than those with moderate or low television consumption.

Dr. Tina Hoang from the Northern California Institute for Research and Education at the International Alzheimer's Congress in Chicago. Assuming a causal connection, excessive television consumption could increase the risk of dementia.

Adjusted results constant

The team around Hoang published the results of the CARDIA study on the effects of TV consumption two and a half years ago. According to this, young adults with a high level of television consumption for more than 20 years later performed significantly worse in various cognition tests than their peers who had only spent a little or moderate amount of time in front of the telly.

Even if physical activity and level of education were taken into account, a negative effect of television could be demonstrated, although this was noticeable to a lesser extent in those participants who still found some time for physical activity despite high television consumption. A lot of television and little exercise - this combination seems to be particularly detrimental to intellectual performance.

In their current analysis, the researchers around Hoang focused on almost 700 participants in the study who had undergone structural brain MRI 25 years after the start of the study. A total of more than 5100 people between the ages of 18 and 30 took part in CARDIA, almost 3500 held out until the last examination. TV consumption was surveyed regularly from the fifth year of study, so that surveys are now available over a period of 20 years.

Morbid TV TV

At the time of the MRI analysis, the participants were 50 years old. On average, over the past two decades, they had stared at the TV screen for 2.3 hours a day, 15% even for four or more hours. Such frequent TV viewers were disproportionately often African American, smokers and people allergic to sports, they also had increased levels of depression, high blood pressure and a low level of education.

If the researchers take age, gender, ethnicity and intracranial volume into account, there was a significant correlation with high television consumption and low total brain volume, low gray matter volume and reduced volume in the frontal lobe. In contrast, other areas such as the hippocampus and entorhinal cortex as well as the white matter showed no decrease in volume depending on television consumption.

Do you need warning notices?

If vascular risk factors such as nicotine and alcohol consumption, obesity, hypertension, depression and physical activity were also taken into account, a significant correlation remained for gray matter in general and the frontal lobe in particular. After that, watching TV actually seems to have a brain-wrecking influence that cannot be explained by little exercise and vascular risk factors alone.

So is it the program? Should there be a warning on talk shows and soap operas like "TV is bad for your mental health?" or "TV makes the brain shrink faster"? Hoang did not want to go that far, but spoke of a lower cognitive reserve in people with high television consumption, due to their sedentary lifestyle. The high TV consumption could only be a marker for such a lifestyle, said the expert.

However, the study did not investigate whether spending a lot of time in front of the computer screen with mostly cognitively demanding activities also had a negative effect on the brain cells. Another major drawback is that there is no imaging data from the start of the study. This would have been able to clarify whether the brain actually shrinks faster in people who watch a lot of TV - unfortunately, a single MRI examination cannot show a chronological sequence.

However, it does not seem plausible that young people with a lower brain volume from the start are more likely to hang in front of the telly. Ultimately, it is more likely that contemporaries who bore their gray cells half the day with shallow conversation will end them prematurely.

the essentials in brief

  • Question: What influence does long-term high television consumption have on brain volume?
  • Answer: The gray matter shrinks faster than with low consumption.
  • Importance: A lot of television could promote dementia.
  • Restriction: Small number of participants, no comparison with other screen activities.