The Interplay of Genetics, Behavior, and Pain with Depressive Symptoms in the Elderly

About 25% of older adults suffer from depressive symptoms. Commonly studied candidate genes associated with depression include those that influence serotonin (SLC6A4), dopamine (COMT), or neuroplasticity (BDNF, NTRK3). However, the majority of candidate gene studies do not consider the interplay of genetics, demographic, clinical, and behavioral factors and how they jointly contribute to depressive symptoms among older adults. The purpose of this study was to gain a more comprehensive understanding of depressive symptoms among older adults.

In this descriptive study, demographic, behavioral, and clinical characteristics (age, gender, comorbidities, volunteering, physical activity, pain, and fear of falling) were obtained via interview of 114 residents in a continuing care retirement community. Peripheral whole blood was collected for DNA extraction. We examined common single nucleotide polymorphisms (SNPs) in the aforementioned genes using path analyses.

SNPs in the NTRK3 gene, pain, physical activity, and fear of falling were directly associated with depressive symptoms in older adults. Those who had polymorphisms in the NTRK3 gene, pain, fear of falling, and were less physically active were more likely to exhibit depressive symptoms. None of the SNPs in SLC6A4, COMT, or BDNF genes were significantly associated with depressive symptoms.

Our use of a path analysis to examine a biopsychosocial model of depressive symptoms provided the opportunity to describe a comprehensive clinical picture of older adults at risk for depressive symptoms. Thus, interventions could be implemented to identify older adults at risk for depressive symptoms.