Frequency of hospitalization for severe depression or bipolar disorder may be associated with increased risk for dementia
The frequency of hospitalization for severe
clinical depression or bipolar disorder may increase the risk of
developing dementia, suggests a study in the December issue of the
Journal of Neurology Neurosurgery and Psychiatry.
The current work was done as a case register
study in Denmark, where the authors were able to review records
for psychiatric hospitalizations between 1970 and 1999. In all,
almost 19,000 patients with depression and just over 4,000 with
bipolar disorder, all of whom were admitted at least once for their
condition, were included in the study.
Analysis of the data showed that a diagnosis
of dementia was strongly related to the number of previous hospitalizations
for either severe depression or bipolar disorder.
Just under 2 percent (337) of patients with
severe depression and just over 2 percent (97) of those with bipolar
disorder were diagnosed with dementia on a subsequent re-admission.
On average, the risk of being diagnosed with
dementia increased 13 percent with every admission to hospital for
severe depression, and by 6 percent with every admission for bipolar
disorder. The findings held even after adjusting for factors likely
to influence the results, such as age and gender.
The authors suggest that repeated episodes
of depression or bipolar disorder may permanently alter brain tissue
(the “scar hypothesis”), as has been suggested in previous research.
They concluded that the results point to
the importance of early and sustained treatment to prevent worsening
of symptoms.
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