The low dopamine hypothesis: A plausible mechanism underpinning residual urine, overactive bladder and nocturia (RON) syndrome in older patients

Aging is associated with a combination of several lower urinary tract (LUT) signs and symptoms, including residual urine, overactive bladder and nocturia. One of the mechanisms of this LUT dysfunction that has not been discussed in dept so far is the role of dopamine (DA). In this narrative review, we explore the dopaminergic hypothesis in the development of this combination of LUT signs and symptoms in older adults. DA is one of the neurotransmitters whose regulation and production is disrupted in aging. In synucleinopathies, altered DAergic activity is associated with the occurrence of LUTS and sleep disorders. Projections of DAergic neurons are involved in the regulation of sleep, diuresis, and bladder activity. The low dopamine hypothesis could explain the genesis of a set of LUT signs and symptoms commonly seen in this population, including elevated residual urine, Overactive bladder syndrome and Nocturia (discussed as the RON syndrome). This presentation is however also common in older patients without synucleinopathies or neurological disorders and therefore we hypothesise that altered DAergic activity because of pathological aging, and selective destruction of DAergic neurons, could underpin the presentation of this triad of LUT dysfunction in the older population. The concept of RON syndrome helps to better understand this common phenotypic presentation in clinical practice, and therefore serves as a useful platform to diagnose and treat LUTS in older adults. Besides recognizing the synucleinopathy “red flag” symptoms, this set of multi-causal LUT signs and symptoms highlights the inevitable need for combination therapy, a challenge in older people with their comorbidities and concomitant medications. Le vieillissement est accompagné d’une association de plusieurs signes et symptômes du bas appareil urinaire (BAU), dont la rétention urinaire, l’hyperactivité vésicale et la nycturie. L’un des mécanismes de ce dysfonctionnement du BAU qui n’a pas été discuté en détail jusqu’à présent est le rôle de la dopamine (DA). Dans cette revue narrative, nous explorons l’hypothèse DAergique dans le développement de cette combinaison de signes et symptômes du BAU chez les personnes âgées. La régulation et la production de la DA sont perturbées dans le vieillissement. Dans les synucléinopathies, l’altération de l’activité DAergique est associée à la survenue de symptômes du BAU et de troubles du sommeil. En effet, différents systèmes DAergiques sont impliqués da