Elderly patients with bipolar disorder (BD) do not show greater levels of cognitive decline over 2 years than their mentally healthy counterparts, research suggests.
Sigfried Schouws (GGZ inGeest, Amsterdam, the Netherlands) and team found that although elderly BD patients had poorer overall cognitive function than controls, there was no significant difference in cognitive decline rates over 2 years between the groups.
The findings, published in Bipolar Disorders, come from a study of 65 euthymic elderly BD outpatients, aged between 60 and 90 years, and 42 mentally healthy individuals of similar age. There were no significant differences between the groups regarding premorbid IQ, education level, or vascular risk factors.
All of the participants underwent a comprehensive neuropsychologic test battery at baseline and at the 2-year follow up to assess attention, learning and memory, executive functioning, and verbal fluency.
The researchers found that patients with BD had significantly poorer mean scores on all cognitive tests than controls both at baseline and at follow up.
For example, in the Trail Making Test-part B, which measures executive function, BD patients took 188.8 and 196.2 seconds to complete the test at baseline and follow up, respectively, compared with corresponding times of 118.86 and 139.14 seconds for controls. And in the Digits Backward test, which measures attention, BD patients scored 3.98 and 3.83 at baseline and follow up, respectively, compared with corresponding scores of 4.64 and 4.36 for controls.
Both groups had poorer scores in all cognitive domains at follow up compared with baseline, but there were no significant between-group differences regarding the magnitude of these declines.
In the BD group, neither illness nor demographic characteristics were associated with cognitive decline in the domains of attention, executive functioning, or learning and memory. However, a greater number of previous hospitalizations predicted greater declines in verbal fluency.
Schouws and team conclude: "Older adults with BD exhibited worse cognitive functioning compared to healthy controls, but no greater cognitive decline over a period of 2 years."
They add that because both groups had comparable vascular risk factors, "it seems there is something inherent in the disease process that results in cognitive impairment, and not simply a manifestation of vascular risk factors."
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