A retrospective study of 13,535 long-term Kaiser Permanente members found that depressive symptoms in mid-life (1964-1973 for this cohort) were associated with a 20% greater risk of developing dementia. Depression in later life (1994-2000) was associated with a 70% increased risk. Depression in both mid- and late-life posed an 80% increased risk. The study appears in the May issue of Archives of General Psychiatry.
"Depression commonly occurs in individuals with cognitive impairment and dementia," the researchers wrote. "Although some studies have found that depression coincides with or follows the onset of dementia in older adults, most studies and several meta-analyses have concluded that depression precedes dementia and is associated with approximately a 2-fold increase in the risk of developing cognitive impairment or dementia."
Note from Kermit Cole, "In the News" Editor:
It is interesting to note the fact that the risk factor for dementia in this cohort is only 20% greater for depression occurring between 1964 and 1973 but there is a 70% increased risk factor for depression occurring between 1994 and 2000. Antidepressants would have been the treatment of choice for depression arising from 1994 to 2000. Apart from any considerations of the specific time-course of the contribution depression might make to the development of dementia, it is reasonable to assume that between 1994 and 2000 most people diagnosed with depression would have received antidepressants.