Before the Sun Goes Down

Researchers learning reasons why elderly experience "sundowning" anxiety delirium

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Elderly adults who live in institutions like nursing homes are more likely to experience a syndrome known as “sundowning”—and now researchers have clues as to why.

Sundowning, seen especially in older adults with dementia, is a phenomenon in which patients have anxiety, agitation and delirium in the late afternoon or evening. In a recent study involving aged mice, researchers found a similar syndrome occurring.

They discovered that these mice experienced changes in the parts of the brain affecting attention, emotions and arousal before bedtime.

"Ask your doctor if a loved one is experiencing "sundowning.""

Previously, some people thought sundowning occurred because elderly patients were frustrated over not being to communicate, or other reasons, said Randy Nelson, the study’s co-author and professor or neuroscience and psychology at Ohio State University.

Now, this study suggests the syndrome has a biological basis, he said.

The aged mice had higher levels of a certain enzyme in the brain before sleep than earlier in the day. High levels of this enzyme is associated with agitation and anxiety.

Doctors have sometimes used medications that regulate this enzyme, known as acetylcholinesterase, to ease the symptoms of sundowning, but didn’t know exactly why it was effective.

Acetylcholinesterase is primarily responsible for terminating communication between nerve signals in the brain and body

The study is slated to appear in the online early edition of the Proceedings of the National Academy of Sciences.

Reviewed by: 
Review Date: 
June 29, 2011
Last Updated:
June 30, 2011