NEW ORLEANS – New-onset depression after hip fracture is fairly common and may be explained in part by certain polymorphisms of the serotonin 1A and 2A receptors, Dr. Eric J. Lenze said in a poster presented at the annual meeting of the American Association for Geriatric Psychiatry.
He and his associates undertook the study to determine whether people with a given vulnerability gene might be more susceptible to late-life depression onset, and hip fracture was considered a good laboratory, Dr. Lenze, of the psychiatry department at the University of Pittsburgh, said in an interview.
Since serotonin is part of the stress response system, the investigators posited that a variation in those receptors might predict a depression response, he added.
They examined 145 older women (median age 81 years) hospitalized after a hip fracture and followed them for a year. Depression and functional status were measured by the Geriatric Depression Scale, the Physical Activities of Daily Living scale, and the Instrumental Activities of Daily Living (IADL) scale. Serum samples also were obtained. The women were genotyped for the risk allele for the two serotonin receptors: 5HTR1A and 5HTR2A.
Women with one to two copies of the risk allele for 5HTR1A had more depression and poorer IADL scores than women without the allele. Dr. Lenze noted the link between depression and bad outcomes.
Interestingly, women with one to two copies of the risk allele for the 2A receptor did not have a higher risk of depression, and they had higher IADL scores after hip fracture, he said.
Dr. Lenze said that the 2A finding might indicate some adaptability afforded by this allele in the 2A receptor, which might help explain why some elderly people are more resistant to the impact of injuries or disease.
The researchers aim to replicate the findings in a larger study and also use them as a springboard to possibly develop a model to help clinicians determine who is at risk for new-onset depression after hip fracture, said Dr. Lenze.