Abstract
Purpose: :
Beginning in the first decade of life, males affected by X-linked Retinitis Pigmentosa (XLRP) progressively lose night vision and peripheral vision. Various degrees of stress and depression may accompany the disease which progressively leads to legal blindness by 20 years of age. This project aims to assess emotional and biochemical stress ancillary to an on-going 4-year randomized clinical trial (RCT) to nutritionally slow the loss of visual function associated with XLRP.
Methods: :
Males (age 7-32 yrs) with established family history of X-linked RP were recruited to participate in the efficacy trial, a subset (n=50) of subjects completed the stress assessments. At 3-month intervals (baseline thru 4 yr), saliva samples were collected and frozen for ELISA analysis of cortisol. A group (n=21) of age and gender-matched controls were recruited to provide normative data. Saliva collection consisted of five samples obtained over a 2-hr time interval after awakening in the morning. The participant was instructed on proper saliva collection in-person and asked to collect the sample at home during a non-stressful time. A time versus cortisol concentration graph was used to calculate six outcomes: AUCG (area under curve ground), AUCB (area under curve baseline), AUCI (area under curve increase), peak cortisol value, average cortisol, and CAR (cortisol awakening response). Surveys of perceived stress (Perceived Stress Scale, Life Events Surveys) were completed annually to assess emotional stress. To maintain RCT masking, only baseline salivary cortisol values and initial survey data were compared between XLRP patients and controls (t-test analysis).
Results: :
The measured AUC parameters (μg/dL/120 min) of waking cortisol for XLRP patients were AUCG 34.5±17.7, AUCB 37.9±19.8, AUCI -3.4±20.6 and did not differ from normal controls (p>0.2). Concentration parameters (μg/dL) [peak cortisol (0.53±0.26), average cortisol (0.28±0.13), and CAR (0.15±0.31)] were also not significantly different in patients (p>0.3). The mean Perceived Stress Scale score (maximum 40 pts) was 14 among XLRP patients (range=1-28) and 14 among normals (range=5-30) suggesting no difference (p>0.6) in the perceived amount of stress experienced by both groups.
Conclusions: :
There have been limited studies of the association of stress and depression in RP or related retinal degenerative diseases. Bittner, et al. (IOVS, 2011) reported an acute increase in salivary cortisol reactivity, higher depression scores and a trend toward higher perceived stress in RP patients. The current study assessing chronic stress found no significant differences between a cohort of XLRP patients and normal controls according to awakening salivary cortisol and perceived stress.
Keywords: retinal degenerations: hereditary • quality of life