| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Dublin, Ireland
To the Editor:
We read with interest the important article by White et al.1 on the pathologic findings in a patient who died with spastic paraplegic gene 4 (SPG4)-linked hereditary spastic paraparesis (HSP) and had a missense mutation in exon 10 of the SPAST gene. This report emphasizes the unique pathologic findings in this patient, who died of a dementing illness and brings to seven the number of families reported with late-onset dementia and HSP linked to chromosome 2p.1-4 This case is extremely important because it is the first to demonstrate the pathologic basis for dementia in SPG4-linked HSP. The findings reported in the article suggest a distinct pathologic process not seen in other dementing conditions. Earlier neuropsychological evidence of a unique dementing process in a large Irish family with HSP linked to SPG42 supports this thesis.
We differ from the authors in their interpretation of the data on the frequency of dementia in SPG4-linked HSP. They suggest that very few SPG4 families manifest this syndrome. Like many clinical phenomena, this disorder will only be found if one looks for it using appropriate clinical tools, including psychometric testing. We contend that cognitive impairment is an intrinsic feature of all families with SPG4-linked HSP. This can be demonstrated by using age-, sex-, and education-matched controls, and is evident from age 40 in such studies using the Cambridge Cognitive Examination (CAMCOG). After age 60 years, the CAMCOG scores for subjects with SPG4-linked HSP drops below 80 (the threshold for dementia), and after 70 years of age, patients show strikingly evident dementia with behavioral changes.4 This is clear in the study by White et al.,1 as they mention that the index patient, as well as his sister and his mother, had memory impairment after age 70 years, according to reports of other family members.
The reason that this dementia has been so infrequently reported is because HSP is a rare disorder, and affected patients, who are often in wheelchairs, are protected by caregivers and not exposed to the usual challenges of new situations. In addition, neurologists have not systematically looked for this disorder. We would suggest that using the appropriate cognitive tests, deficits may be detected at least in the seventh decade of life. Perhaps a collaborative study between American and European clinicians with access to these families would be worthwhile.
Footnotes
Copyright © 2001 by AAN Enterprises, Inc.
References
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
