It has been reported that elderly subjects have a compromised ability to produce melatonin nightly, and that reduced melatonin levels may be a risk factor for cancer. The purpose of this study was to evaluate the relationship between melatonin levels and chronic diseases in a cohort of elderly subjects using the Charlson comorbidity index (CCI).Design:
We performed a secondary data analysis of a longitudinal study of a representative, age-stratified, sample population.Setting:
The Treviso Longeva (Trelong) study, in Treviso, Italy.Participants:
A total of 114 men and 146 women, aged 77 years and older, still alive after 7 years of follow-up.Measurements:
As an estimation of serum melatonin secretion levels, urinary 6-sulfatoxymelatonin (aMT6s) was assayed in the urine of 260 elderly subjects using an enzyme-linked immunosorbent assay (ELISA) kit (product 01-EK-M6S, ALPCO Immunoassays, Windham, NH). All aMT6s levels were creatinine standardized ([aMT6s]/[creatinine]), and the CCI was calculated.Results:
The melatonin levels decreased with aging despite not reaching statistical significance, and the decrease was more evident in males than in females (40.5 ng vs 47.0 ng aMT6s/mg creatinine, ns). Melatonin levels were significantly lower in patients reporting insomnia (p=0.05). The CCI score was inversely correlated with the levels of melatonin (p=0.03). Melatonin levels of subjects affected by CCI pathologies were significantly lower than those of healthy subjects (p=0.03) and of subjects suffering from diseases not included in the CCI and, therefore, less severe (p=0.03).Conclusion:
Melatonin appears to be a marker of disease state and severity, as well as of sleep disorders, in the elderly. These early findings would confirm the protective role of melatonin against several chronic diseases. The benefits of this agent as a possible medication should be more thoroughly clinically tested.