A comparison between the neurocognitive profile of Huntington Disease-Like 2 and Huntington Disease: Exploring the presence of double dissociations

Abstract

Huntington Disease Like-2 (HDL2) is a rare autosomal dominant genetic disease caused by a mutation in the JPH3 gene. HDL2 is the Huntington Disease (HD) phenocopy that has the greatest clinical resemblance to HD. Both are characterized by movement, psychiatric and cognitive dysfunction, which progress to dementia. The present study compared the neuropsychological profile of HDL2 with that of HD. Using a Single Case-Control Methodology in Neuropsychology, three HDL2 and seven matched HD patients were assessed with a comprehensive neuropsychological battery and compared to matched control samples, considering age, years of education, type of school (public/government) and language (all bi/multilingual). Potential double dissociations were explored by using Crawford, Garthwaite, and Wood's Inferential Methods for Comparing the Scores of Two Single-Cases in Case-Control Designs. Double dissociation between HDL2 and HD were identified in three tests, namely Letter Number Sequencing, Rey Auditory Learning Test Delayed and Recognition Trials. These dissociations possible are due to methodological limitations.

Keywords:

• HDL2
• HD
• neuropsychological assessment
• neuropsychology
• case study

Acknowledgments

This report is partially based on the unpublished PhD thesis of the first author. Reference: Ferreira-Correia, A. (2019). The Neurocognitive Profile of Huntington Disease-Like 2: A Comparison with Huntington Disease and Healthy Controls. (PhD), University of the Witwatersrand, Johannesburg, South Africa. We are sincerely grateful to the participants, especially to the patients and their families, and to Mrs. Marianne Gomes who provided genetic counseling to all potential clinical participants.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 “Mixed ancestry individuals, in South Africa, are those whose gene pool is derived from one or more of the indigenous African populations (San, Khoikhoi or Bantu speaking), European immigrants from western Europe and/or slaves and indentured labourers from Madagascar, the Malaysian archipelago and India”. “Black individuals are those whose gene pool is derived from one or more of the indigenous Bantu-speaking African populations” (Krause et al., 2015, p. 1).

Additional information

Funding

This study was partially supported by the Medical Research Council of South Africa Self-Initiated Research Grant awarded to Prof. Amanda Krause.