Researchers at the Institute of Applied Ophthalmobiology (IOBA), University of Valladolid, Spain, has reported results on the use of hair cortisol concentrations (HCC), measuring chronic stress among RP patients. The research was aimed to support patients with Retinitis pigmentosa (RP), which researchers had reported negative psychological states of stress due to their progressive and unpredictable loss of vision. Following their study, HCC appeared to provide an effective biomarker associated with chronic stress of RP patients and the measurement may also be useful as a potential outcome measure for treatments for retinal degeneration.
The clinical researchers recruited seventy-eight (78) RP patients and 148 healthy controls, conducting a complete ophthalmological exam including visual acuity, SD-OCT and visual field (VF). The patients graded as being severe or mild, in terms of symptoms, and all patients assessed the perceived stress and trait anxiety test, measured by the “State-Trait Anxiety Inventory” (STAI) questionnaire. In addition, cortisol was extracted from hair samples and measured by ELISA. The results showed that fifty-two (67%) patients had severe RP and twenty-six (33%) had mild-moderate RP. Fifty-eight (58,9%) patients reported severely levels of stress and eighteen (23.,1%) highly levels assessed by STAI questionnaire. RP patients exhibited higher HCCs (500.04 ± 120.99 pg/mg) than in controls (136.17 ± 60.51 pg/mg; p < 0.001). Severe RP patients had significant higher HCCs than mild-moderate patients differing in 274.27 pg/mg (p < 0.001). Group differences were not affected by relevant covariates (age, grade of severity, stress status, and gender).
The HCC measurement was logarithmically transformed and presented below: (A) patients with RP had a higher level of cortisol in the hair samples (2.62 ± 0.14 Log10 pg/mg), compared with the controls (1.99 ± 0.23 Log10 pg/mg; p < 0.001); (B) patients with mild / moderate RP had a lower level of cortisol (2.43 ± 1.17 Log10 pg/mg), compared with severe RP (2.71 ± 0.12 Log10 pg/mg; p < 0.011), and; (C) a high anxiety level had a lower level of cortisol (2.49 ± 0.19 Log10 pg/mg), compared with the severe anxiety (2.70 ± 0.24 Log10 pg/mg; p < 0.001):
This study was aimed to evaluate the relationship between chronic stress, anxiety and cortisol levels, “and revealed that HCC in patients with RP were significantly different when compared to healthy controls”. The researchers showed that there were differences in HCC in RP patients in relation to their different grades of severity and anxiety status and this “may be useful in monitoring anxiety and stress and could be a sensitive tool for identifying patients at risk of higher stress and thus, more risk of suffering fluctuations in their vision”. Finally, the biomarker for HCC itself may be useful for assessing treatments for RP clinical trials, and potentially wider for other retinal degenerations.