In a report strengthening the connection between mood disorders, dementia and Alzheimer's disease, researchers found that depressed individuals who'd begun to experience cognitive decline progressed into full Alzheimer's sooner than their emotionally unaffected peers. Depression seemed to be the key influence in this equation and related medications reduced or negated the statistical disparity.

The study behind the report concerned 756 individuals, aged 55 to 91, who'd experienced cognitive impairment beyond that seen in most healthy seniors. Researchers at UCLA determined that 208 of these subjects suffered from clinical depression according to a standard mood disorder test, and these affected parties were significantly more likely to have been diagnosed with Alzheimer's disease  by the 3-year study's end. In fact, each subject's chances of developing AD was directly related to the severity of his or her depression. The likelihood of an AD diagnosis within the given time frame rose 3% for each point on the depression scale.

Further data confirmed the complimentary relationship between depression and AD: the main purpose of the study was to ascertain the preventive powers of popular AD drug Aricept (donepezil), which has been known to improve symptoms but cannot eliminate the condition and has only approved for the treatment of advanced AD. Researchers found that subjects medicated with Aricept for the entire study experienced a considerably lower instance of the disease (14%) than those placed in a corresponding placebo group (29%). The drug interestingly had little or no effect on the development of AD in non-depressed subjects.

Researchers could not effectively highlight the science behind their finding - but their data implies that Aricept is very effective in delaying the most pronounced symptoms of Alzheimer's disease for some patients. If similar evidence continues to build the FDA may feel pressure to approve the drug for the treatment of pre-AD cognitive problems. This study simply reinforces the nature of the relationship between two complimentary disorders: by weakening the immune and neurological systems, severe depression allows unrelated degenerative disorders to more powerfully assert their influence. Any senior experiencing an abnormal degree of cognitive impairment who also displays symptoms of clinical depression should consider seeking further treatment.