Increased hippocampal plaques and tangles in patients with Alzheimer disease with a lifetime history of major depression
Rapp MA, Schnaider-Beeri M, Grossman HT, Sano M, Perl DP, Purohit DP, et al.;
Commented by , 23 Jun 2006
Background
A large number of population based studies from the general population as well as some studies of patients with recurrent depression suggest that depression is a risk factor for developing dementia and Alzheimer disease. The hallmark pathological changes in Alzheimers disease (AD) are abundant plaque and tangle formation, especially in the temporal lobes and hippocampus. However, there have been no studies of neuropathological changes in AD as a function of history of major depression.
Method
This is a postmortem study of the brains of a total of 102 patients with AD comparing the brains of 52 patients with AD without a lifetime history of major depression with the brains of 50 patients with AD with a lifetime history of major depression. Assessment of a history of depression before onset of AD was done using medical information, including charts and information obtained from the treating physician.
Neuropathological ratings from the Consortium was used to establish a Registry in Alzheimer Disease battery.
Results
Brains of patients with AD with a lifetime history of depression showed significantly higher levels of both plaque and tangle formation within the hippocampus compared with brains of patients with AD without a history of depression. Patients with AD who had a history of depression exhibited more rapid cognitive decline than patients without a history of depression.
Professor Kessing's comments
This is the first study to investigate possible neurophatology behind the association between depression and AD. The findings are surprisingly consistent:
- the presence of a lifetime history of depression corresponded to increases in AD-related neuropathological changes within the hippocampus
- the neuropathological changes were associated with more rapid cognitive decline in patients with AD with a history of depression
- the neuropathological changes were more pronounced in patients with AD suffering from depression early on in the disease process.
This is very interesting results that for sure needs replication by other researchers and among other samples of patients than nursing home patients and with earlier age at death than the average age of 81 years (SD: 8) in the present study. Similarly, it is of great interest to investigate whether the neuropathological abnormalities increase with the number of depressions as suggested by a recent epidemiological study (ref. 1).
References
1. Kessing LV, Andersen, PK. Does the risk of developing dementia increase with the number of episodes in patients with depressive disorder and in patients with bipolar disorder? Journal of Neurology, Neurosurgery and Psychiatry 2004; 75; 1662-1666 (Free full text article)