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IC‐P‐136: APATHY AND REDUCED STRIATAL UPTAKE IN DEMENTIA WITH LEWY BODIES
Author(s) -
GraffRadford Jonathan,
Lowe Val J.,
Kantarci Kejal,
Jones David,
Peller Patrick,
Przybelski Scott,
Ferman Tanis J.,
Bennett Jamie,
Smith Glenn,
Aakre Jeremiah,
Pankratz Ver,
Knopman David S.,
Petersen Ronald Carl,
Boeve Bradley F.
Publication year - 2014
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2014.05.142
Subject(s) - apathy , dementia with lewy bodies , depression (economics) , putamen , anxiety , medicine , psychology , dementia , psychiatry , cardiology , audiology , cognition , disease , economics , macroeconomics
matching, using permutation of a large pool of control participants. Methods: 25 patients with mild cognitive impairment (MCI) and 39 healthy elderly underwent diffusion MRI. The fornix, parahippocampal cingulum (PHC) and uncinate fasciculus (UF) were reconstructed by tractography. Measures of fractional anisotropy (FA) and mean diffusivity (MD) were derived from each tract. 100 random samples of 20 controls were generated from the group of healthy participants. Tract measures and demographics (age, years of education, verbal IQ) were compared between each sample and the MCI group. Additionally, samples were generated by including the extremes for each demographic variable. The proportion of samples that showed a significant group difference was calculated as a proxy of power for each tract-metric pair (uncorrected p<.005 to account for multiple comparisons). Results: A decrease in fornix FA in MCI was found for 98% of randomly-generated samples indicating a power of 0.98 without attention to matching variables. In contrast, power to detect MD increases in left and right UFwere 0.47 and 0.58 respectively. Only group differences in PHC FA were demonstrated in samples that showed no significant difference in mean age (Figure). Imperfections in age matching contributed to observed group differences in all tracts. In contrast, education and IQ matching had little impact on observed differences in fornix and right PHC. Conclusions: The quality of case-control matching influences the power to detect differences in individual white matter tracts. These biases vary across tracts and diffusion metrics. Age had a consistent effect on perceived effect size but education and IQ influenced comparisons only for certain tracts. Conclusions about spatial patterns of alteration in case-control designs require a sensitivity analysis that is based on an understanding of the effects of confounding factors on the specific tracts in question.