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ARTICLES: Mona K. Beyer, Jan P. Larsen, and Dag Aarsland Gray matter atrophy in Parkinson disease with dementia and dementia with Lewy bodies Neurology 2007; 69: 747-754 [Abstract] [Full text] [PDF]

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Gray matter atrophy in Parkinson disease with dementia and dementia with Lewy bodies

Steven R. Brenner, None   (4 December 2007)

Reply from the authors

Mona K. Beyer, MD, Dag Aarsland   (4 December 2007)

Gray matter atrophy in Parkinson disease with dementia and dementia with Lewy bodies 4 December 2007
Steven R. Brenner, Departments of Neurology at the St. Louis VA Medical Center and St. Louis University Medical Center St. Louis VA Medical Center, 915 North Grand, St. Louis, MO 63106, None Send Correspondence to journal: Re: Gray matter atrophy in Parkinson disease with dementia and dementia with Lewy bodies SBren20979{at}aol.com Steven R. Brenner, et al.	I read the article by Beyer et al with interest. [1] Parkinson disease (PD) may be divided into two types: a “subcortical” subtype characterized by frontal impairment with apathy and dullness and a “cortical” subtype with symptoms similar to those of Lewy body dementia (DLB). The degree of cortical dementia may differ among Parkinson patients as well as between Parkinson patients and DLB patients. [2] Differentiating between the “subcortical” subtype of dementia and DLB may be more practical than differentiating all cases of PD from DLB. Although the voxel-based morphology on the MRI appears helpful in analyzing cortical atrophy, measuring the thickness of the brain at its narrowest point, from lateral ventricular surface to the cortical surface often correlates well with the degree of cerebral atrophy and dementia. Often measures of brain thickness on MRI brain imaging from the lateral ventricular posterior horn surface to the cortical surface at the depth of a cortical sulcus in the parietal and occipital region is less than a centimeter in demented patients. This measure includes both cortical and subcortical structures and often seems to correlate well with cerebral atrophy and dementia. A simple measurement of brain thickness from ventricular to cortical surface, at specific regions or lobes of the brain, may assist in determining the degree of brain atrophy associated with different neurodegenerative diseases such as Alzheimer, Parkinson and DLB. References 1. Beyer M, Larson J, Arsland D. Gray matter atrophy in Parkinson disease with dementia and dementia with Lewy bodies. Neurology. 2007;69:747-754. 2. Meyniel C, Damier P. Lewy body dementia and Parkinson disease dementia. Presse Med. 2007 Jun 13 [Epub ahead of print] [Article in French]. No conflicts of interest. Disclosure: The author reports no conflicts of interest.
Reply from the authors 4 December 2007
Mona K. Beyer, MD, Stavanger University Hospital PO Box 8100, 4068 Stavanger, Norway, Dag Aarsland Send Correspondence to journal: Re: Reply from the authors bemk{at}sus.no Mona K. Beyer, MD, et al.	We thank Dr. Brenner for his interest in our work. [1] We agree that there is heterogeneity both clinically and pathologically within PDD and also DLB groups, and it is important to explore the brain-behavioral relationships in these syndromes. However, this would require larger groups of patients than we studied. In addition to the differences mentioned, we recently found a different pattern of atrophy in PD patients who developed dementia early versus late after onset of PD (Beyer, submitted), in line with a recent autopsy study. [3] We agree that there is a need for simple measures to distinguish between different dementia syndromes and encourage studies exploring the utility of this and other measures. However, given the involvement of different brain regions in the neurodegenerative dementias, we believe more than one measure is probably needed to accurately differentiate these diseases, as has been previously shown with measures (e.g. of the medial temporal lobes). [4] Localization and degree of atrophy and the comparison of regional differences between the different types of dementia are interesting both for diagnostic purposes, but also for increasing our knowledge about the changes taking place in the brain in the course of the disease. This can also give valuable information about the localization of atrophy associated with cognitive impairment and other symptoms commonly occurring in dementia. In order to achieve such knowledge, we believe that a single measurement of brain thickness is not enough. References 3. Ballard C, Ziabreva I, Perry R, et al. Differences in neuropathologic characteristics across the Lewy body dementia spectrum. Neurology 2006;67:1931-1934. 4. Tam CW, Burton EJ, McKeith IG, Burn DJ, O'Brien JT. Temporal lobe atrophy on MRI in Parkinson disease with dementia: a comparison with Alzheimer disease and dementia with Lewy bodies. Neurology 2005;64:861-865. Disclosure: The authors report no conflicts of interest.