Continuing the series on ‘Purpose in Life’ today’s post involves a brief look at some of the research exploring the relationship between depressive illness and purpose in life. I used the PubMed interface for Medline and combined the search terms “purpose in life” and depression which produced 72 results. In this cross-sectional study people with advanced illneses including cancer and chronic obstructive pulmonary disease (COPD) completed the Spiritual Well-Being Scale and the Centre for Epidemiologic Studies Depression Scale (CESDS). The researchers found a significant inverse correlation between the number of symptoms of depression and increasing spiritual well-being (the Spiritual Well-Being scale includes purpose in life as a subscale). However it is more difficult to establish causality in cross-sectional studies.
In a Swedish study looking at older adults the researchers used the Purpose in Life test. They found a significant relationship between depression at baseline and lower PIL score 5 years later. However there was no difference between those with and without depression at baseline in PIL scores. They concluded that living with depression over five years was associated with a loss of purpose in life. Depression might intuitively be expected to affect meaning and purpose in life but the baseline results are difficult to interpret in this context. Another possibility might be that a demoralisation syndrome (see discussion here) might have some overlap with depression in this population although the former construct is not yet formally recognised as a diagnostic entity in the diagnostic manuals. The study is also described in this paper (the researchers note that the cohort is between 85 and 103 years of age) where the authors conclude that high PIL scores do not reduce the risk of developing depression at five years. However in this prospective study by a group in Manchester (n=5566) lower positive well-being scores were correlated with depression at 10 years (CESDS and SPWB were used). Perhaps the longer follow-up period was significant here. Purpose in life (ikigai) was one of the factors significantly contributing to caregiver burden in a Japanese study looking at 193 caregivers of older adults.
A large Japanese cross-sectional study (n=10969) involved administering the CESDS and a questionnaire that examined 21 life stressors. The researchers found that depression scores were associated with loss of purpose in life (although the strongest relationship between depressive symptoms and life stressors was having nobody to talk to). Students from five universities were assessed in another Japanese study (n=545) but interestingly purpose in life subscale scores on the SPWB did not correlate with HADS scores (Hospital Anxiety and Depression Scores). Thus from the above studies there is some evidence of a relationship between depression and purpose in life. Although not all studies found an inverse relationship between measures of depression and purpose in life at baseline there were associations with baseline scores on purpose in life at baseline and depression at follow-up although two studies provided different results. There is a standardisation in studies with a preference for the SPWB and the use of the CESDS with a number of studies having large sample sizes. However based on the above studies alone there is much to be clarified about the relationship between depression and purpose in life and the emergence of demoralisation syndrome as an illness construct may provide a useful contrast for further clarifying this relationship.
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