To Daydream or Not
Does too much daydreaming or, if you will, too much unfocused time contribute to Alzheimer’s?
The researchers compared PET scans, MRI images, and other data from 764 participants with dementia, mild dementia, or no dementia. The images revealed that posterior cortical regions of the brain, including the posterior cingulated, retrosplenial, and lateral parietal cortex, were active in the “default state” of young adults without dementia. They were also the regions attacked by amyloid plaques in older adults with Alzheimer’s.
The “default state” is the term Dr. Buckner and colleagues use to describe the brain’s activity when it is not concentrating on a particular task but musing, daydreaming, or retrieving pleasant memories.
The study also found that metabolic abnormalities and atrophy emerged in these daydreaming areas of the brain during the early stages of Alzheimer’s.
Even the brain’s relatively inactive daydreaming mode requires considerable energy, and the researchers speculated that an accumulated lifetime of metabolic activity might lead to wear and tear that disposes default areas of the brain of the brain to amyloid deposition, metabolic disruption, and atrophy.
Let me, then, suggest an alternate hypothesis: amyloid plaque invasion represents an atrophy of the posterior cortical regions. In other words it is an underuse phenomena that has as its proximal cause radio, television, stereos, mp3 players, etc. Time folks once spent in the default state has been preempted by the always on sounds of these devices. It should be fairly easy to determine whether default state activity is turned off when listening/watching these devices.
Another unintended consequence of the always on society may be an overall reduction in creativity, even overall cultural intelligence. Test this yourself. If you always have something on, even just for background when you are cooking, doing the dishes, jogging, etc., turn it off for 30 minutes a day. Over the course of a week observe the difference in the quality of your mental activity during the off time. Some of you may not be able to handle the intensity of the change. But that’s part of the point.
Update 8/26: Lindsay Beyerstein comments on this as do her commentors.