Number of neurons associated with sleep in neurodegenerative conditions

A new study investigates whether the number of neurons in the brain’s subcortical region is related to specific sleep patterns in participants with Alzheimer’s disease or progressive supranuclear palsy. 

As the body’s control center, the brain is an extremely complex organ that differs slightly between everyone.  However, some types or regions of neurons, the cells in the brain, are associated with certain cognitive functions.  For example, subcortical neurons, or neurons in the area below the cerebral cortex responsible for more complex cognitive processes, are believed to help control behavior and motor functions.^1,2

Interestingly, studies suggest that neurodegenerative conditions, such as Alzheimer’s disease (AD) and progressive supranuclear palsy (PSP), may be associated with premature degeneration of subcortical neurons.^2,3  A variety of sleep disturbances are also frequently observed in AD and PSP patients.^4,5  

Despite these findings, it is unknown whether the severity of subcortical neuron degradation in AD and PSP is associated with these sleep disturbances.  To address this, a study was performed on AD and PSP patients.  The results were recorded and published to JAMA Neurology.²  

Firstly, researchers took and examined different brain scans of the participants to determine subcortical neuron counts.  Next, they analyzed a variety of sleep-related metrics, such as total sleep time, sleep maintenance, and time spent in different sleep stages, to determine the presence of sleep disturbances in the participants.²

Researchers gathered data from 33 participants with AD, 20 participants with PSP, and 32 participants with neither condition.²  The data from ten participants with AD and nine participants with PSP were used in the final analysis comparing subcortical neuron counts and sleep disturbances.  Within this group, ten participants were female, and all participants were caucasian.²  

The study found that subcortical neuron counts were correlated with more regular sleep patterns in the participants with AD and PSP.²  These findings could potentially suggest that decreased subcortical neuron counts may be associated with decreased sleep balance in people with these conditions, so this warrants further research. 

Some limitations of this study include the small sample size and lack of racial diversity within the participants, as this makes the findings less likely to apply to a larger general population.  More research is needed to confirm the significance of this association, as well as measures that can be taken to prevent adverse effects on AD and PSP patients. 

References

1. Tekin, S., Cummings, J.L. (2002, August). Frontal-subcortical neuronal circuits and clinical neuropsychiatry: an update. J Psychom Res 53(2): 647-654. Doi: 10.1016/s002-3999(02)00428-2.
2. Oh, J.Y., Walsh, C.M., Ranasinghe, K., et al (2022, April 4). Subcortical neuronal correlates of sleep in neurodegenerative diseases. JAMA Neurol. Doi: 10.1001/jamaneurol.2022.0429
3. Arendt, T., Bruckner, M.K., Gertz, H., et al (2015, February 10). Early neurone loss in Alzheimer’s disease: cortical or subcortical? Acta Neuropathologica Communications 3(10). Doi: 10.1186/s40478-015-0187-1
4. Brzecka, A., Leszek, J., Ashraf, G.M., et al (2018). Sleep disorders associated with Alzheimer’s Disease: A Perspective. Front Neurosci 12:330. Doi: 10.3389/fnins.2018.00330
5. Walsh, C.M., Ruoff, L., Walker, K., et al (2017, November). Sleepless night and day, the plight of progressive supranuclear palsy. Sleep 40(11). Doi: 10.1093/sleep/zsx154

Image by Gerd Altmann from Pixabay