Mult Scler. 2016 Aug 19. pii: 1352458516663854. [Epub ahead of print]
Fatigue and fluid hydration status in multiple sclerosis: A hypothesis.
Fatigue is a prevalent and functionally disabling symptom for individuals living with multiple sclerosis (MS) which is poorly understood and multifactorial in etiology. Bladder dysfunction is another common MS symptom which limits social engagement and quality of life. To manage bladder issues, individuals with MS tend to limit their fluid intake, which may contribute to a low-hydration (LoH) state and fatigue.
To evaluate the relationship between patient-reported MS fatigue, bladder dysfunction, and hydration status.
We performed a prospective cross-sectional study in 50 women with MS. Participants submitted a random urine sample and completed several fatigue-related surveys. Using a urine specific gravity (USG) threshold of 1.015, we classified MS subjects into two groups: high-hydration (HiH) and LoH states.
LoH status was more common in MS subjects with bladder dysfunction. Statistically significant differences in self-reported Fatigue Performance Scale were observed between HiH and LoH subjects (p = 0.022). USG was significantly correlated with fatigue as measured by the MS Fatigue Severity Scale (FSS) score (r = 0.328, p = 0.020).
Hydration status correlates with self-reported fatigue, with lower fatigue scores found in those with HiH status (USG < 1.015).
Not infrequently, patients tell me that they restrict their fluid intake because of bladder problems. But is this worsening their MS?
Fatigue in MS occurs mainly later in the day, made worse by heat and exertion. And based on the findings of this study fluid hydration state can affect fatigue levels, with higher levels of hydration being protective against MS-related fatigue. Moreover, the effect of even small changes in hydration state in MS may be a scale magnitude higher in MS owing to underlying autonomic issues. It’s not surprising then that hot weather can exacerbate fatigue levels in conjunction with a low hydration status.
The skeptical may point out that more severe bladder problems, such as incontinence, is more common in those with more disabling MS who are also less likely reach a toilet with ease, and so is fatigue. But in 2012, a study in young women also found that dehydration impacted adversely on vitality, fatigue, perception of task difficulty, concentration and headache (Armstrong LE et al. Mild dehydration affects mood in healthy young women. J Nutr 2012; 142(2): 382-388).
Therefore, good hydration is a very low risk intervention and easily incorporated into other programs directed at fatigue.