SLEEP DISORDERS IN VASCULAR DEMENTIA AND MILD COGNITIVE IMAPAIRMENT
Copil Alexandra, Vladoi Adina, Munteanu Georgiana, Birdac Claudiu, Anghel Alexandra, Dan Flavius, Jianu Dragos Catalin OBJECTIVES
GENERALITIES
POLYSOMNOGRAPHY
SLEEP DISORDERS - associated with dementia - associated with MCI CONCLUSION OBJECTIVES
Determine whether disrupted daytime activity and altered sleep patterns predict development of mild cognitive impairment (MCI) or dementia [6] [8]
Clarify whether patients with MCI demonstrate alterations in certain sleep parameters [5]
Focus on identification of sleep disorders in the context of cognitive disturbances among professionals working with the elderly [7]
Investigate and describe frequency and characteristics of sleep disorders in pacients with cognitive disorders [3] [4] [7]
Review the predictive roles of overall sleep disturbances and other sleep problems [1] GENERALITIES
There is a well-known relationship between neurodegenerative disease, disrupted sleep, and cognition. [6] Sleep disturbances and dementia are two common and significant health problems in older adults. [1] Compared with individuals without sleep disturbances, subjects who reported sleep disturbances had a higher risk of incident all-cause dementia, AD, and vascular dementia. [1][2] The mild cognitive impairment (MCI) is described as an intermediate state of cognitive impairment whereby individuals present with mild clinical symptoms but with nearly normal daily living activities. These subjects do not meet the clinical criteria for dementia, yet their cognitive functioning is below what we would expect for age and education in healthy people. [7] Sleep disturbance (especially sleep apnea syndrome- SAS) also occurs in patients with mild cognitive impairment (MCI) and is considered to be one of the predictive risk factors. Sleep disturbance appears to be involved in the cellular and molecular mechanisms of cognitive decline [5] [8] In the other hand, older adults are at risk for sleep disorders including obstructive sleep apnea syndrome, restless legs syndrome, REM sleep behavioral disorder and chronic insomnia, which could have an impact on cognitive functioning and are exclusion criteria for the MCI diagnosis. [7] POLYSOMNOGRAPHY: Definition
Polysomnography is a comprehensive recording of the biophysiological changes that occur during sleep. The test result is called a polysomnogram, also abbreviated PSG. [10] It is usually performed at night, when most people sleep, though some labs can accommodate shift workers and people with circadian rhythm sleep disorders and do the test at other times of day. The PSG monitors many body functions, including brain activity (EEG), eye movements (EOG), muscle activity or skeletal muscle activation (EMG), and heart rhythm (ECG), during sleep. [10] Polysomnography is used to diagnose, or rule out, many types of sleep disorders, including idiopathic hypersomnia, periodic limb movement disorder (PLMD), REM behavior disorder, parasomnias, and sleep apnea. [10] Although it is not directly useful in diagnosing circadian rhythm sleep disorders, it may be used to rule out other sleep disorders. [10] POLYSOMNOGRAPHY: Mechanism A polysomnogram will typically record a minimum of 12 channels requiring a minimum of 22 wire attachments to the patient. [10] There is a minimum of three channels for the EEG, one or two measure airflow, one or two are for chin muscle tone, one or more for leg movements, two for eye movements (EOG), one or two for heart rate and rhythm (ECG), one for oxygen saturation, and one each for the belts, which measure chest wall movement and upper abdominal wall movement. [10] Wires for each channel of recorded data lead from the patient and converge into a central box, which in turn is connected to a computer system for recording, storing and displaying the data. [10] During sleep the computer monitor can display multiple channels continuously. In addition, most labs have a small video camera in the room so the technician can observe the patient visually from an adjacent room. [10] POLYSOMNOGRAPHY: Procedure For the standard test, the patient comes to a sleep lab and over the next 1–2 hours is introduced to the setting and "wired up" so that multiple channels of data can be recorded when he/she falls asleep. [10] During the study, the technician observes sleep activity by looking at the video monitor and the computer screen that displays all the data second by second. [10] The patient would sleep with the screening device for one to several days, then return the device to the health care provider. [10] The provider would retrieve data from the device and could make assumptions based on the information given. For example, series of drastic blood oxygen desaturations during night periods may indicate some form of respiratory event (apnea). The equipment monitors, at a minimum, oxygen saturation. [10] After the test is completed a "scorer" analyzes the data by reviewing the study in 30-second "epochs". [10] POLYSOMNOGRAPHY: Interpretation
The score consists of the following information: o Onset of sleep from time the lights were turned off: this is called “ sleep onset latency" and normally is less than 20 minutes. [10] o Sleep efficiency: the number of minutes of sleep divided by the number of minutes in bed. Normal is approximately 85 to 90% or higher. [10] o Sleep stages: these are based on 3 sources of data coming from 7 channels: EEG (4 channels), EOG (2), and chin EMG (1). [10] o Each 30-second epoch is scored as "awake" or one of 4 sleep stages: 1, 2, 3, and REM, or Rapid Eye Movement, sleep. o Stages 1–3 are together called non-REM sleep. Non-REM sleep is distinguished from REM sleep, which is altogether different. Within non-REM sleep, stage 3 is called "slow wave" sleep” because of the relatively wide brain waves compared to other stages OR "deep sleep". By contrast, stages 1 and 2 are "light sleep". [10] "Arousals" are sudden shifts in brain wave activity. They may be caused by numerous factors, including breathing abnormalities, leg movements, environmental noises, etc. An abnormal number of arousals indicates "interrupted sleep" and may explain a person's daytime symptoms of fatigue and/or sleepiness. [10] o Cardiac rhythm abnormalities. o Leg movements. o Body position during o Oxygen saturation duringsleep. sleep. Once scored, the test recording and the scoring data are sent to the sleep medicine physician for interpretation. Ideally, interpretation is done in conjunction with the medical history, a complete list of drugs the patient is taking, and any other relevant information that might impact the study such as napping done before the test. [10] Any breathing irregularities, mainly apneas and hypopneas. Apnea is a complete or near complete cessation of airflow for at least 10 seconds followed by an arousal and/or 4% oxygen desaturation; hypopnea is a 30% or greater decrease in airflow for at least 10 seconds followed by an arousal and/or 4% oxygen desaturation. [10] SLEEP DISORDERS: Types of disturbances
Sleep and circadian disorders occur frequently in all types of dementia [2] Are common in dementia, with problems including difficulty falling asleep or staying asleep, sleep fragmentation, wandering and excessive daytime sleepiness. [9] Sleep is one of the cornerstones of human wellbeing, and reduced or poor-quality night-time sleep can significantly impact daytime functioning and quality of life [9] A careful clinical evaluation of sleep disorders should be performed routinely in the clinical setting of persons with cognitive decline. [3] In most cases, the sleep disturbances evaluated are: insomnia, excessive daytime sleepiness (EDS), REM behavior disorder (RBD), restless legs syndrome (RLS), and nightmares [3][9], sleep disordered breathing [SDB]), and other sleep problems (e.g. circadian rhythm sleep disorder, and nonspecific sleep problems) [1] SLEEP DISORDERS IN DEMENTIA
Within dementia, the causes of sleep disorders can be – as in people without dementia – physical health conditions, pain or discomfort, medications or anxiety or depression. In addition, there are often disturbances of the circadian rhythm (including early sleep onset and offset or late sleep initiation and rise time) [9] The neurodegenerative changes in vascular dementia but not only, affect the structure and functioning of relevant brain networks. [9] Pathologic and imaging studies have shown that regions in the brain shown to regulate sleep and circadian rhythm are abnormal in VaD and AD. [6] Most of the studies enroll patients with different subtypes of dementia: Alzheimer's disease (AD), vascular dementia (VaD), mixed dementia, mild cognitive impairment (MCI), dementia with Lewy bodies (DLB), Parkinson's disease dementia (PDD), and frontotemporal lobar degeneration (FTLD) [3] Every type of sleep disorder was present in each type of dementia but with significant differences. Insomnia increased the risk of AD but not vascular or all-cause dementia. In contrast, SDB was associated with a higher incidence of vascular dementia and all-cause dementia (considered risk factor) [1]
Frequency of RDB was associated more with VaD. RLS and nightmares were recognized mainly in FTD, LBD, and PDD patients scores [3]
There are also the patients with VCIND that are compared with control subjects and simple stroke patients. [4] o Studies have been made and the PSG revealed that patients with VCIND or stroke were more likely to experience prolonged sleep latency (SL), decreased sleep efficiency (SE), increased arousal, reduced deep sleep and rapid eye movement (REM) sleep than controls so that abnormal sleep in VCIND may be associated with cognitive impairment (MOCA score should be performed) [4] SLEEP DISORDERS IN MCI
Recent evidence suggests that sleep habits are differentially compromised in different subtypes of MCI, but the relationship between sleep disruption and MCI remains poorly understood. [6]
Compared with healthy elders, overall MCI patients as a group expressed more sleep latency and less sleep efficiency; MCI patients showed less total sleep time. [5] Patients with MCI have a frequency of sleep disturbances of any type equal to that of patients with VaD presenting mostly SDB or REM behaviour disorder [3]
Amnestic MCI patients (aMCI) are predisposed to less disturbed sleep than both nonamnestic MCI (naMCI) and cognitively intact subjects, as measured objectively by movement in bed at night. In addition, the aMCI group has less day-to-day variability in these measures than the intact and naMCI patients. [5] [6] In general, the naMCI patients showed a level of disturbed sleep that was intermediate to that of aMCI and intact subjects. These differences in sleep disruption between aMCI and naMCI may be related to differences in the pathology underlying these MCI subtypes. [5] [6] SLEEP APNEA SYNDROME
Sleep apnea syndrome (SAS) is considered a risk factor for cognitive decline in the elderly (especially in patients with MCI). [8]
Results show that poor sleep quality and greater severity of SAS were associated with impaired language function reflecting frontal- subcortical pathology in patients with MCI (vulnerability to a specific brain damage associated with SAS could increase the risk for dementia) [8] CONCLUSION
A careful clinical evaluation of sleep disorders should be performed routinely in the clinical setting of persons with cognitive decline [3]
Sleep disorders in dementia affect emotional and physical health, may worsen cognitive symptoms, and reduce quality of life for those with dementia and their family members. [9]
Disrupted daytime activity and altered sleep-wake patterns may predict transition to mild cognitive impairment or dementia [1] [6]
The results indicate that MCI patients might experience more serious sleep disturbance and that different MCI subtypes have different patterns of sleep disturbance. [5]
These findings may help identify individuals who are at risk for dementia and optimize early prevention strategies. [1] [1] Shi L1, Chen SJ2, Ma MY3, Bao YP4, Han Y4, Wang YM5, et all. Sleep disturbances increase the risk of dementia: A systematic review and meta-analysis. Sleep Med Rev. 2018 Aug;40:4-16. doi: 10.1016/j.smrv.2017.06.010. Epub 2017 Jul 6. [2] Ooms S1,2, Ju YE3. Treatment of Sleep Disorders in Dementia. Curr Treat Options Neurol. 2016 Sep;18(9):40. doi: 10.1007/s11940-016-0424-3. [3] Pistacchi M1, Gioulis M, Contin F, Sanson F, Marsala SZ. Sleep disturbance and cognitive disorder: epidemiological analysis in a cohort of 263 patients. Neurol Sci. 2014 Dec;35(12):1955- 62. doi: 10.1007/s10072-014-1870-x. Epub 2014 Jul 18. [4] Jiang B1, Ding C, Yao G, Yao C, Zhang Y, Ge J, et all. Polysomnographic abnormalities in patients with vascular cognitive impairment-no dementia. Sleep Med. 2013 Nov;14(11):1071-5. doi: 10.1016/j.sleep.2013.07.003. Epub 2013 Sep 16. [5] Hu M1, Zhang P1, Li C1, Tan Y2, Li G1, Xu D1, et all. Sleep disturbance in mild cognitive impairment: a systematic review of objective measures. Neurol Sci. 2017 Aug;38(8):1363-1371. doi: 10.1007/s10072-017-2975-9. Epub 2017 Apr 28. [6] Hayes TL1, Riley T, Mattek N, Pavel M, Kaye JA. Sleep habits in mild cognitive impairment. Alzheimer Dis Assoc Disord. 2014 Apr-Jun;28(2):145-50. doi: 10.1097/WAD.0000000000000010. [7] Bayard S1. [Mild cognitive impairment: could it be a sleep disorder?]. Geriatr Psychol Neuropsychiatr Vieil. 2015 Sep;13(3):317-27. doi: 10.1684/pnv.2015.0555. [8] Kim SJ1, Lee JH, Lee DY, Jhoo JH, Woo JI. Neurocognitive dysfunction associated with sleep quality and sleep apnea in patients with mild cognitive impairment. Am J Geriatr Psychiatry. 2011 Apr;19(4):374-81. doi: 10.1097/JGP.0b013e3181e9b976. [9] Kinnunen, Kirsi M.; Vikhanova, Anastasia; Livingston, Gill. The management of sleep disorders in dementia: an update. Current Opinion in Psychiatry, 2017 Nov;30(6):491-497. doi; 10.1097/YCO.0000000000000370 [10] Medscape 2018, Polysomnography, https://emedicine.medscape.com/article/1188764-overview#