[Sleep disorders in the early stage of Parkinson's disease in untreated patients]

Correction of the wake-sleep cycle by intranasal administration of dopamine in modeling of the preclinical stage of Parkinson's disease in rats

Sleep disorders, which are among the earliest and most sensitive non-motor manifestations of Parkinson's disease (PD), are not diagnosed in 40–50 % of patients and are not subject to the necessary correction. In this regard, the ineffectiveness of a late start of treatment, when more than 50 % of dopamine-producing neurons are already affected, dictates the need to search for and develop approaches to the prevention and slowdown of neurodegenerative pathology at the preclinical stages of its development using adequate experimental models. Taking into account the low bioavailability of dopamine (DA) and data on the advantages of the intranasal route of administration in comparison with oral and parenteral methods of drug delivery to the CNS, the aim of the work was to study the neurophysiological features of the wake-sleep cycle as early manifestations of nigrostriatal insufficiency and the effect of intranasal administration of DA on the quality of sleep during the formation of the preclinical stage of PD in rats. It was shown that under the conditions of modeling PD, the cyclic organization of sleep with a predominance of incomplete cycles against the background of hyperproduction of slow-wave sleep and REM phases are early manifestations of nigrostriatal insufficiency. Course administration of DA at a dose of 3 mg/kg is accompanied by the normalization of sleep quality in the form of reduction (by 76 %) in the number of incomplete cycles. The preventive orientation of the obtained effects may indicate a certain therapeutic potential of intranasal delivery of DA to the brain, aimed at slowing down the processes of neurodegeneration and possibly delaying its clinical manifestation

[Age-related differences in sleep disturbances in rat models of preclinical Parkinson's disease]

OBJECTIVE

To describe the changes in temporal characteristics of sleep-wake cycle, which can serve as non-motor manifestations of an early stage of Parkinson's disease (PD), using the model of preclinical PD in rats of two age groups.

MATERIAL AND METHODS

A prolonged (up to 21 days) model of preclinical PD in middle-aged (7-8 month) and aged (19-20 month) rats was created. The model was based on cumulative inhibition of proteasomal system of the brain caused by intranasal administration of lactacystin, a specific proteasome inhibitor. Polysomnographic data were recorded daily using telemetric Dataquest A.R.T. System (DSI, USA) in unrestrained animals.

RESULTS AND CONCLUSION

Aging was accompanied with increased sleepiness during the active (dark) phase of the day (as was implied by a two-fold increase in the total time of drowsiness) and with 1.5-fold growth of light sleep during the inactive phase of the day. A common feature of sleep disturbances in the model of preclinical PD in both middle-aged and aged rats was hypersomnia during the active phase of the day. It was suggested to be similar to the excessive daytime sleepiness in humans. Hypersomnolence was more pronounced in aged rats because it added to sleepiness developing with aging. In both age groups, the model of preclinical PD was also associated with a decrease in EEG delta power during slow-wave sleep. It is considered dangerous because it might represent the decrease in protein synthesis rate and the weakening of restorative processes in neurons, occurring with the prolonged inhibition of proteasomal system of the brain. Sleep disturbances, identified the model of preclinical PD in rats of different age, may be recommended for clinical validation as low-cost early signs indicating the initial stage of PD.

Nighttime sleep disorders in patients with daytime sleepiness in Parkinson s disease

Daytime sleepiness is one of the clinically significant non-motor manifestations of Parkinson's disease (PD). One of its insufficiently studied aspects is a relationship between daytime sleepiness and nighttime sleep disorders.

Objective:to clarify the clinical characteristics of PD in patients with different types of daytime sleepiness and to estimate of the ratio of daytime sleepiness to clinical and polysomnographic characteristics of nighttime sleep in patients with advanced stages of PD.

Patients and methods. The investigation included 110 patients (56 men and 54 women) (mean age, 63.78+0.6 years) with PD (Hoehn and Yahr stage 2.6+0.2; disease duration, 6.3+3.2 years) without dementia. All the patients received therapy with levodopa at a mean daily dose of 667.8 mg; 98 of them had the drug in combination with dopamine receptor agonists at a stable dose. The unified PD rating scale, the PD sleep scale (PDSS), and the Epworth sleepiness scale (ESS) were applied. Nocturnal polysomnography (PSG) and the multiple sleep latency test (MSLT) were performed.

Results and discussion. There was daytime sleepiness in 44% of the patients: permanent sleepiness in 15%, sudden daytime sleep attacks (along with low daytime sleepiness (ESS) in 14%, and permanent drowsiness concurrent with sleep attacks in 15%. The PSG findings showed a decrease in sleep efficiency, an increase in the duration of the first stage of sleep, a reduction in the duration of the second and third sleep stages, an extension of rapid eye movement (REM) sleep latency, and frequent awakenings (sleep fragmentation). PSG also demonstrated REM sleep behavior disorders (RBD) in half of the examinees.

Patients with sleep attacks differed from those with permanent drowsiness without sleep attacks with more severe sleep disorders (PDSS) and shorter sleep latency (MSLT). Patients with the RBD phenomenon had shorter sleep latency (MTLS) than those without this parasomnia. Patients with moderate or severe sleepiness (ESS scores of >10) differed from those with milder drowsiness (ESS scores of 410) and a lower representation of the third sleep stage.

Conclusion.There is evidence for the association of daytime sleepiness in PD with reduced efficiency, changes in the nighttime sleep pattern, and RBD.