Ataxia is complex; the diverse symptoms it presents makes every individual’s experience uniquely challenging. As a person ages, determining whether changes are caused by Ataxia or unrelated causes can be difficult, especially when symptoms impact the way a person thinks and feels.
It is important to understand Ataxia’s impact beyond the physical or visible symptoms. Historically, the effects of Ataxia on cognitive abilities are understudied and can be overlooked. It is in this context that we celebrate a significant achievement in Ataxia research. “The Cerebellar Cognitive Affective / Schmahmann Syndrome Scale in Spinocerebellar Ataxias,” a recent publication on a study led by Principal Investigators Dr. Jeremy Schmahmann and Dr. Louisa Selvadurai, marks a pivotal moment in our understanding of Ataxia’s broader effects.
Dr. Schmahmann and his colleagues were kind enough to offer us a lay summary of their research paper to share with the Ataxia community. Check that out below.
“Thank you to NAF and the Macklin Foundation for support and encouragement, and to the patients and their families in CRC-SCA without whom this work could not be completed.”
– Dr. Jeremy Schmahmann
Measuring How We Think: A Tool for Identifying Cognitive Challenges Faced by People with Ataxia
A lay summary of: The Cerebellar Cognitive Affective / Schmahmann Syndrome Scale in Spinocerebellar Ataxias
Cognitive skills, or thinking skills such as attention, memory, and reasoning ability, play an important role in our everyday activities. In spinocerebellar Ataxias, the changes that occur to the brain may lead to changes in these cognitive skills. Researchers have been looking for a way to better measure cognitive skills in people with Ataxia. The Cerebellar Cognitive Affective Syndrome/Schmahmann Syndrome (CCAS) Scale was developed to identify cognitive changes amongst people with spinocerebellar Ataxias and other conditions that impact the cerebellum. Since its publication in 2018, the scale has been translated into more than 15 languages and used to test individuals with several different cerebellar conditions.
There has been growing evidence that individuals with spinocerebellar Ataxias perform more poorly on the CCAS Scale compared to unaffected individuals. However, not everyone with a spinocerebellar Ataxia shows cognitive difficulties. So, we still have more to learn about how common the CCAS is amongst this group.
Selvadurai and colleagues, investigated this question by looking at CCAS Scale performance amongst individuals who participated in two large natural history studies in the USA – the CRC-SCA and READISCA studies. This included 309 symptomatic individuals with SCA1, SCA2, SCA3, SCA6, SCA7, or SCA8. They compared the cognitive performance of these individuals to two other groups: control and pre-symptomatic individuals. There were 37 controls individuals without spinocerebellar Ataxia. Twenty-six individuals were pre-symptomatic with SCA1 or SCA3. Pre-symptomatic individuals have the gene that causes Ataxia, but do not yet have Ataxia symptoms.
The researchers found that 46% of symptomatic individuals with SCAs met the criteria for having the CCAS. This means that they were having challenges with cognitive skills. However, 5.4% of the controls also met the criteria for having the CCAS. This means there was a small false positive rate, where a test incorrectly identifies someone as having a health condition.
As a group, symptomatic individuals showed poorer cognitive performance on the CCAS Scale compared to controls and pre-symptomatic individuals. Furthermore, the more severe a symptomatic person’s Ataxia symptoms were, the worse their cognitive performance tended to be. A person’s age and level of education also influenced their cognitive performance. These findings highlight that cognitive changes are quite common in spinocerebellar Ataxias. This data also shows how the CCAS Scale can be an important tool to help identify these cognitive changes. Early identification of cognitive changes can allow healthcare professionals to provide appropriate advice and support for people with Ataxia.
Study Citation
Selvadurai LP, Perlman SL, Ashizawa T, Wilmot GR, Onyike CU, Rosenthal LS, Shakkottai VG, Paulson HL, Subramony SH, Bushara KO, Kuo SH, Dietiker C, Geschwind MD, Nelson AB, Gomez CM, Opal P, Zesiewicz TA, Hawkins T, Yacoubian TA, Nopoulos PC, Sha SJ, Morrison PE, Figueroa KP, Pulst SM, Schmahmann JD. The Cerebellar Cognitive Affective/Schmahmann Syndrome Scale in Spinocerebellar Ataxias. Cerebellum. 2024 Jan 2. doi: 10.1007/s12311-023-01651-0. Epub ahead of print. PMID: 38165578.
