PHILADELPHIA – Patients with mild to moderate Alzheimer's disease have a faster rate of cognitive decline as they accumulate more symptoms of depression, Ann Marie Hake, M.D., reported in a poster at the Ninth International Conference on Alzheimer's Disease and Related Disorders.
This relationship held regardless of the patient's gender or the treatment received, said Dr. Hake, a neurologist at the Indiana University Center for Aging Research, Indianapolis.
The patients Dr. Hake and her associates studied were enrolled in a trial with the primary aim of testing the efficacy of transdermal selegiline. Cognition of all patients was assessed at baseline and after 48 weeks of treatment using the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog). The study failed to show a significant treatment effect of selegiline on cognition among the 265 patients who completed 48 weeks of treatment.
All patients were also assessed for depression at baseline using the Hamilton Depression Scale. Symptoms of depression were assessed during the study and at week 48 using the Cornell Scale for Depression.
When average changes in the ADAS-cog scores over the 48 weeks were correlated with changes in the Cornell depression scores, the researchers found a highly significant, positive association: As the Cornell total score increased from baseline through week 48, the patients' decline in cognition became greater, Dr. Hake reported at the conference, which was presented by the Alzheimer's Association.
The degree of depression at baseline did not predict the extent of deterioration in cognition over the following 48 weeks.
Results from several prior studies have shown a link between depression and dementia, but this study provides additional information about the nature of this relationship. Depression affects 20%–30% of people older than 65 years; more than 60% of elderly people with depression do not receive treatment.
Among people with dementia, up to 20% have major depression and up to 30% have dysthymia, she said.