Why dementia patients "sundown"

Have you heard of "sundowning"? The term refers to dementia and Alzheimer's patients who seem to get suddenly worse (agitated/anxious/mean/angry/confused) late in the afternoon or in the early evening.

Although doctors do have medicine to treat the symptoms, it hasn't been clear why sundowning occurs. But a recent study might offer some insight.

Researchers found that aged mice who experienced sundowning (like humans) demonstrated changes in parts of their brain associated with attention, emotions and arousal. And mice that were genetically engineered with Alzheimer's had more anxiety before sleep.

The test used two groups of mice. One group was "middle aged" (7 months old) and the other group was "old age" (29 months = a human in his 80s).

The middle-aged mice had three peaks of activity while they were awake. But the aged mice had a flattened rhythm of activity. So when the middle-aged mice slowed down before sleep, the aged mice kept going.

Late in the day, the aged mice put out higher levels of a certain enzyme that causes anxiety and agitation. In addition, the brain researchers saw spikes of two other enzymes (that cause behavioral disturbances) in the brains of the aged mice during sundowning. 

Here's the study:

http://www.medicalnewstoday.com/releases/229757.php

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