In brief: Compensatory changes in the brain may help people with ALS maintain cognitive efficiency according to a new study.
Think tank. Researchers discovered that functional changes in certain regions of the brain (blue) may help some people with ALS maintain cognition. Image: Agosta et. al (2012), Neurobiology of Aging. All rights reserved.
ALS is a progressive neurodegenerative disease in which the motor nerves deteriorate resulting in muscle weakness and paralysis.
A growing number of studies suggest however that ALS extends well outside the motor cortex, the region of the brain that controls the movement of muscles. Neuroinflammation, triggered by the disease, spreads throughout the brain, possibly short-circuiting other key control centers including those that contribute to cognition.
Nevertheless, all people with ALS struggle with muscle weakness. But only about half of these patients show any signs of cognitive impairment.
Now, a new study led by San Raffaele Scientific Institute neuroimaging specialist Massimo Filippi MD in Milan may explain why cognition might be spared in some people with ALS. The scientists discovered using resting state functional magnetic resonance imaging (rs-fMRI) that unaffected regions of the brain might “step up to the plate” to help maintain critical thinking abilities.
This is the first study to correlate functional changes in the ALS-ravaged brain to levels of cognition.
The results are published this month in Neurobiology of Aging.
The research team examined the brains and thinking abilities of 16 people with probable or definite sporadic ALS without frontotemporal dementia (FTD).
The scientists found that people with ALS who performed better on executive function tests exhibited higher levels of functional connectedness in the default mode and frontoparietal networks of brain. These areas of the brain are critical for a number of cognitive abilities including planning, remembering and thinking ahead.
The results suggest that certain networks in the brain might kick into overdrive to help maintain cognitive function in people with ALS over the course of the disease. Larger studies however are needed to confirm these conclusions.
To learn more about how cognition might be affected in people with ALS, read C9ORF72 Comes Into Focus. To find out how resting state fMRI could help neurologists better understand and diagnose the disease, check out MRI Make That a Double.
Agosta ,F., Canu, E., Valsasina, P., Riva, N., Prelle, A., Comi, G. and Filippi M.J. (2012) Divergent brain network connectivity in amyotrophic lateral sclerosis. Neurobiology of Aging, doi: 10.1016/j.neurobiolaging.2012.04.015. Abstract | Full Text (Subscription Required)
Phukan, J,. Elamin, M., Bede, P., Jordan, N., Gallagher, L., Byrne, S., Lynch, C., Pender, N. and Hardiman O. (2012) The syndrome of cognitive impairment in amyotrophic lateral sclerosis: a population-based study. Journal of Neurology, Neurosurgery and Psychiatry 83(1), 102-108. Abstract | Full Text
Brettschneider, J., Libon, D.J., Toledo, J.B., Xie, S.X., McCluskey, L., Elman, L., Geser, F., Lee, V.M., Grossman, M. and Trojanowski, J.Q. (2012) Microglial activation and TDP-43 pathology correlate with executive dysfunction in amyotrophic lateral sclerosis. Acta Neuropathologica 123(3), 395-407. Abstract | Full Text (Subscription Required)
Phukan, J, Pender, N.P. and Hardiman O. Cognitive impairment in amyotrophic lateral sclerosis. Lancet Neurology 6, 994-1003. Abstract | Full Text (Subscription Required)