The biological process of aging may contribute to the risk of depression and anxiety in older adults, according to a study recently released by the Columbia University Mailman School of Public Health and Peking University School of Public Health. Nearly all previously studies have focused on the reverse: poor mental health as a risk factor of accelerating aging.
The Columbia and Peking researchers computed biological ages by applying algorithms used to predict disease, disability and mortality to blood chemistries of 424,299 midlife and older adults in the UK Biobank, a medical database. They then tested the associations of biological ages with depression and anxiety. UK Biobank’s participants were recruited in 2006–2010 at ages 37 to 73 and have since received multiple follow-ups.
The study findings, published online in Nature Communications, showed that adults of more advanced biological age were more likely to experience depression and anxiety at baseline than their peers who were the same chronological age but tested as biologically younger. During an 8.7-year follow-up, the researchers closely analyzed what had become of the 369,745 participants who did not have depression and anxiety at the outset of the study:
“Among older adults who were free of depression/anxiety at baseline, those whose blood indicated that they were biologically older than their chronological age would predict were more likely to develop depression or anxiety over follow-up compared with those whose blood indicated that they were biologically younger,” Xu Gao, PhD, assistant professor at Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, China, and the study’s first author, said in a press release from the Mailman School of Public Health.
“This study helps confirm that identifying risk factors and mechanisms of vulnerability to mental disorders must be a public health priority,” continued Gao, who had been affiliated with the Columbia Mailman School Department of Environmental Health Sciences.
Increased disability and mortality
Depression and anxiety are common, often co-occur and are associated with increased disability and mortality, especially in older adults, said the release. It also noted that preventing depression and anxiety in older adults can potentially mitigate disease burden in an aging population.
The study also found that people with depression/anxiety experienced higher incidence of chronic conditions over follow-up as compared with those who did not have depression/anxiety (for diabetes, 6% vs. 3%; for cardiovascular diseases, 12% vs. 6%; and for cancers, 11% vs. 8%.)
The study did not not address the mechanisms mediating the link between accelerated biological aging and depression/anxiety, which they said could be formed at multiple stages in the progression of aging processes.
“We all age at the same rate in chronological terms. But from a biological perspective, some of us age faster than others, developing chronic disease and disability much earlier and living shorter, sicker lives,” senior author Belsky,PhD, associate professor of epidemiology at Columbia Mailman School of Public Health and a member of the Butler Columbia Aging Center, said in the release. “Findings suggest future directions for depression/anxiety risk assessment in older adults as well as the potential for therapies that target the biology of aging to contribute to the prevention of later-life depression/anxiety.”
Stronger associations for men
Did the sex of the study participants with accelerated biological aging influence how likely they were to experience depression and anxiety? Rethinking65 asked.
“Yes, in one of our sensitivity analyses, for PhenoAge acceleration, associations were somewhat stronger for men as compared with women,” Gao replied through the Mailman School of Public Health. “You can find the findings on page 4 of the paper.”
The Columbia and Peking researchers also believe socioeconomic status may have influenced how likely participants were to experience depression and anxiety, but more study is needed.
The UK Biobank used the Townsend Index of Deprivation to estimate socioeconomic status. . The index is a composite score based on four key variables — unemployment, overcrowded household, non-car ownership and non-home ownership.
“We did not directly look into this question,” Gao replied through the Mailman School. “Townsend deprivation index was estimated by UK Biobank team. We cannot have the four raw variables as they were confidential and only the index was accessible in the UK Biobank.”
“But based on the results of Models 2 and 3, the additional adjustment of Townsend somehow attenuated the effects. A potential influence might exist and could be studied in our future studies,” said Gao.