Depression linked to physical pain years later

(Press-News.org) Middle-aged and older adults who experience pain are more likely to have had worsening symptoms of depression up to eight years before the pain began, according to a new study by UCL (University College London) researchers.

The study, published in the journal eClinicalMedicine, suggests that among this age group, treatment for depression might help to prevent or reduce later aches and pains.

The researchers compared survey data from 3,668 adults aged over 50 who often experienced moderate to severe pain with a matched group of the same number who did not.

In the pain group, they found that depressive symptoms got rapidly worse in the eight years prior to pain, peaked at the onset of pain, and remained high in the years after, whereas in the non-pain group depressive symptoms were less severe, less prevalent, and relatively constant.

The researchers found a similar trend for loneliness, which increased both in the years before and years after the onset of pain but stayed low and relatively constant for those in the non-pain group.

While the cause of the pain was not identified, most participants said they had pain in the back, knee, hip, or foot.

Lead author Dr Mikaela Bloomberg (UCL Epidemiology & Public Health) said: “Pain and depression are known to be linked, with each exacerbating the other. But we don’t know about the timing of these related conditions.

“Our study shows that depressive symptoms and loneliness worsen long before pain begins. This is important as it suggests the potential for early mental health and social support to reduce or delay later pain.

“Factors such as depression and loneliness can contribute to pain through several mechanisms. By inducing stress, they may increase inflammation, which can lead to pain. They also may increase sensitivity to pain by changing immune responses and by dysregulating our autonomic nervous system, the network of nerves that control unconscious processes such as the ‘flight or fight’ response.

“Our findings highlight the importance of approaching pain not just from a biological perspective. Mental health interventions may be important too.”

The study used data covering 21 years from the English Longitudinal Study of Ageing (ELSA), in which a nationally representative population sample in England answers a wide range of questions every two years.

The research team found that the sharp increase in depressive symptoms among participants who experienced pain was larger among people with less education and wealth. This is likely in part, the researchers said, because these individuals had fewer resources to support mental health and pain management.

The team said this finding pointed to the need to prioritise vulnerable populations with fewer socioeconomic resources with accessible mental health and community support programmes.

The researchers also investigated if there was a link between social isolation and experiences of pain but, unlike with loneliness, found little difference in social isolation between the pain and non-pain groups.

Whereas loneliness is a subjective feeling of lacking social connections, social isolation indicates objective lack of contact with friends and family. The team suggested that the quality of relationships, rather than the quantity of relationships or levels of social interaction, may matter in terms of mitigating against pain and depression.

Three quarters of the study participants in the pain group reported experiencing pain in the back, knee, hip, or foot. Of those remaining, 1.9% reported pain all over, 0.5% reported mouth or tooth pain, and 20.7% reported pain elsewhere.  

Among study limitations, the research team noted that the participants were overwhelmingly white, reflecting the population of England in that age group. Future research, they said, should determine whether results are similar for younger groups and those with more racial and ethnic diversity.

They cautioned that the survey data did not distinguish between pain and chronic pain. However, they had consistent results when they restricted the analysis to participants who reported pain in successive surveys two years apart, suggesting the findings applied to chronic pain.

The team adjusted for a wide range of factors that may have skewed the results – including participant sex, age, birth year, education, wealth, long term health conditions, physical activity level, alcohol consumption and smoking status.

The researchers received funding from the Nuffield Foundation’s Oliver Bird Fund and Versus Arthritis. The English Longitudinal Study of Ageing is funded by the National Institute on Aging and by a consortium of UK government departments coordinated by the National Institute for Health and Care Research.

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