The researchers said this could be because older patients are either reluctant to volunteer psychological or emotional symptoms or believe that such problems are a normal part of life.
The study also found that GPs were less likely to enquire about symptoms of depression in older people.
The study’s authors wrote: ‘Health professionals working in primary care should have a higher index of suspicion for older people given the higher prevalence of depression in this population’.
The researchers undertook a meta-analysis to compare the accuracy of diagnoses for those over the age of 60 with those under it.
At a depression prevalence rate of 17% (typical of an urban area), the study estimates that 73% of over 60s will be correctly diagnosed, compared with 79% of under 60s.
GPs correctly identified a greater proportion of older depressed individuals (47% compared to 40% of under 60s), but failed to rule out depression in a higher proportion of cases for the elderly (79% vs. 85%).
According to the study’s authors, this means a large proportion of elderly people are being falsely diagnosed with depression. They estimate that in an area with 17% prevalence, 18% of over 60s would be falsely diagnosed as depressed, compared with a 12% false positive rate in the under 60s.