Older men with a history of depression may be at greater risk of developing dementia than those without current or past depression, but it appears that depression in later life is more likely a marker of incipient dementia rather than a truly modifiable risk factor, according to a report in Translational Psychiatry.
Surprisingly, the authors noted that the use of antidepressants did not decrease the risk of dementia associated with depression.
“Older people with depression may be better viewed as potential targets of indicated prevention strategies [for dementia], rather like people with mild cognitive impairment,” Osvaldo Almeida, M.D., Ph.D., of the University of Western Australia and colleagues wrote.
Data were drawn from the Health In Men Study, a community-based cohort study based in Western Australia. Researchers used voting rolls to recruit a sample of 12,203 men aged 65 to 84 years living in Perth in 1996. During a second wave of assessments between 2001 and 2004, 5,514 participants provided information about depressive symptoms and past history of depression. The final study sample consisted of 4,922 men aged 71 to 89 years who were free of dementia/cognitive impairment. They were followed until the onset of dementia, death, or through the end of June 2015, whichever occurred first.
Participants were followed, on average, for 8.9 years. During this time, 903 men received the diagnosis of dementia (18.3%) and 1,884 died free of dementia (38.3%). The adjusted hazard ratio of dementia among men who had ever been depressed (past or current), men with a past history of depression only, and men with current depression was 1.3, 1.3, and 1.5, respectively. Moreover, the researchers also found that there was a graded association between the severity of depressive symptoms and the risk of dementia, with the risk being more pronounced for men with severe depression.
Importantly, however, the association between depression and dementia was limited to the first five years of follow-up—a finding the authors wrote “suggest[s] that depression may represent a prodromal manifestation of cognitive impairment, rather than one of its causes.” A total of 302 men (6.1%) were using antidepressants at the time of the assessment, but the use of antidepressants did not appear to decrease the risk of dementia.
“It is conceivable that depression with onset in early or mid-life could contribute to modulate the risk of dementia later in life, whereas depression arising in older age may be more frequently an early manifestation of an underlying neurodegenerative process,” Almeida and colleagues wrote.
For related information, see the Psychiatric News article “Neuropsychiatric Symptoms Implicated in Conversion from MCI to Dementia.”
Live Mentally Healthy,
Dr. Jennie Byrne