Alzheimer's Symptoms And Depression Do Not Change Together

While there is a correlation between individuals with depression and
the development of Alzheimer's disease, it appears that the symptoms of
depression do not increase in the years before an Alzheimer's
diagnosis, according to a report released on April 7, 2008 in the
JAMA/Archives journal Archives of General Psychiatry.




Previous studies have shown that patients with Alzheimer's or its
precursor, mild cognitive impairment, have higher levels of depressive
symptoms, which include feeling sad or a diminished ability to feel
pleasure. According to the article, this association's causality is not
clear. "The basis of this
association is uncertain, however," the authors write. "A leading
hypothesis is that depressive symptoms do not constitute a true risk
factor but rather a consequence of the disease." If hypothesis was
true, the symptoms of depression would coincide with the symptoms of
Alzheimer's, and thus increase in the early stages of the disease.



To investigate the cause of the correlation, Robert S. Wilson, Ph.D.,
of Rush University
Medical Center, Chicago, and colleagues examined older Catholic nuns,
priests, and monks who did not have dementia. A total 917 patients were
examined beginning in 1994. They were evaluated early
by: neurological examination; cognitive exam investigating
thinking, learning, and memory; classification for Alzheimer's disease
or mild cognitive impairment; and a ten item scale to access their
symptoms of depression.



When the study began, 53.6% of participants presented no symptoms of
depression, 23.9% reported one symptom, 9.7% reported two, 6.1%
reported three, and 6.8% reported more. In the later examination, 20.7%
of the individuals (190) developed the disease. If someone displayed
symptoms of depression at the beginning of the study, he was more
likely to develop Alzheimer's disease by the end.



However, the levels of symptoms did not change at the same time: "those
who developed Alzheimer's
disease showed no increase in depressive symptoms before the diagnosis
was made, and this finding was not modified by age, sex, education,
memory complaints, vascular burden or personality," say the authors.
"Among those without cognitive impairment at baseline, depressive
symptoms did not increase in those who subsequently developed mild
cognitive impairment." This indicates that depression is not a
consequence of Alzheimer's, but rather a risk factor for the
development of dementia.



The authors offer the explanation that depression may intrinsically
change the brain to make it less resistant to dementia. They add:
"Understanding the mechanisms linking depressive
symptoms with dementia could suggest novel approaches to delaying
dementia onset because animal research suggests diverse means by which
the adverse effects of chronic stress may be modified."



Change in Depressive Symptoms During the Prodromal Phase of
Alzheimer Disease

Robert S. Wilson, PhD; Steven E. Arnold, MD; Todd L. Beck, MS; Julia L.
Bienias, ScD; David A. Bennett, MD

Arch Gen Psychiatry. 2008;65(4):439-445.

Click
Here For Abstract



Written by Anna Sophia McKenney