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Regional cerebral blood flow changes in patients with Alzheimer disease during performance of a Stroop task
ABSTRACTS
Regional cerebral blood flow changes in patients with Alzheimer disease during performance of a Stroop task K. Villringer 1, Ch. Hock 2, S. Minoshima 4, R. Wenzel3,I. Wolf 1, S. Ziegler l, C. Kruschke 1, F. Miiller-Spahn 1, A. Villringer 3, M. Schwaiger 1 JDept. of Nuclear Medicine, Technical University of Munich, Germany, :Dept. of Psychiatry, University of Basel, Swizzerland, Dept. of Neurology, Humboldt-University, Berlin, Division of Nuclear Medicine, The University of Michigan, Ann Arbor, Michigan, USA Purpose:
Alzheimer's disease (AD) affects predominantly regions of the temporo-parietal and frontal association cortex. Those regions are identified in PET or SPECT studies as regions of decreased brain metabolism and blood flow at rest. It is not known how these and other brain regions behave under activated conditions. In the present study we therefore assessed changes in CBF as measured by PET during performance of a Stroop task in subjects with moderate or severe Alzheimer disease as compared to healthy control subjects. Patients and Methods:
We examined 10 patients with Alzheimer's disease (median age 76 ys.) and 6 healthy controls (median age 58 ys.). Repeated measurements of CBF were perfomed using a H2150-bolus technique with a 951 R/31 PET Scanner (Siemens CTI, Knoxville TN, USA) in 2D mode (axial field of view of 10.8 cm). PET image sets were obtained at rest and during performance of a stroop task. The colour of the presented word was identical with the written word (congruent) or did not match the written word (incongruent) in randomized order. Subjects were instructed to name the colour and not to read the presented word. Images were normalized, coregistered, resliced and stereotactically transformed as described previously by Minoshima et al. [1, 2]. Differences between the control and activation images were expressed as voxel-by-voxel t-statistic values using a pooled variance [3]. Clusters ofpixel exhibiting a Z-score above 3.1 in the control group were used to create 21 3D-templates for subsequent ROl-analysis using the unsmoothed stereotactically transformed substraction finages normalized to global cerebral activity. For comparison of patients and normal controls unpaired t-test was performed. Results:
21 regions defined by significant CBF increase during performance of the Stroop task in the control subjects were analyzed for CBF changes in Alzheimer subjects. Statistically significant differences were found in 2 regions. These regions showed a reduced cerebral blood flow already under resting conditions. In the right inferior parietal lobe a CBF flacrease of 17.4 • in normal subjects was contrasted by a drop of-5.02 • % in Alzheimer subjects. In the left superior temporal gyrus a 21.4% • rCBF increase in normal subects was seen as opposed to a -5.6 • 13.0 % decrease in Alzheimer patients. T-statistic maps didn't reveal any activation in the entire right parietal lobe in the AD-group. This contradicts the assumption that these findings are only based on minor differences in localization of activation foci between the groups. Table 1
Anatomical location
Volume of the 3D ROl
Tailarach coordinates
Inf. Parietal lobe R Sup. Temporal gyrus L
0.5 ml 0.2 ml
-44, -40, 43 64, -24, 14
mean rCBF changes in control 17.4i14.3 21.4•
mean rCBF changes in patients -5.02• -5.6•
p-value
=0.001 =0.001
Conclusions:
Brain activation differs significantly between normal subjects and patients with Alzheimer's disease. Our results indicate that in particular areas with reduced cerebral blood flow under resting conditions may be activated less under stimulated conditions. References
1. Minoshima S, Berger KL, Lee KS, Mintun MA. J Nucl Med 1992;33:1579-1585 2. Minoshima S, Koeppe RA, Mintun MA, Berger KL, Taylor SF, Frey KA, Kuhl DE. J Nucl Med 1993;34:322329 3. Worsley K J, Watson JD, Lueck CJ et al. J Cereb Blood Flow Metab 1992; 12:900-918 $520
Regional cerebral blood flow changes in patients with Alzheimer disease during performance of a Stroop task K. Villringer 1, Ch. Hock 2, S. Minoshima 4, R. Wenzel3,I. Wolf 1, S. Ziegler l, C. Kruschke 1, F. Miiller-Spahn 1, A. Villringer 3, M. Schwaiger 1 JDept. of Nuclear Medicine, Technical University of Munich, Germany, :Dept. of Psychiatry, University of Basel, Swizzerland, Dept. of Neurology, Humboldt-University, Berlin, Division of Nuclear Medicine, The University of Michigan, Ann Arbor, Michigan, USA Purpose:
Alzheimer's disease (AD) affects predominantly regions of the temporo-parietal and frontal association cortex. Those regions are identified in PET or SPECT studies as regions of decreased brain metabolism and blood flow at rest. It is not known how these and other brain regions behave under activated conditions. In the present study we therefore assessed changes in CBF as measured by PET during performance of a Stroop task in subjects with moderate or severe Alzheimer disease as compared to healthy control subjects. Patients and Methods:
We examined 10 patients with Alzheimer's disease (median age 76 ys.) and 6 healthy controls (median age 58 ys.). Repeated measurements of CBF were perfomed using a H2150-bolus technique with a 951 R/31 PET Scanner (Siemens CTI, Knoxville TN, USA) in 2D mode (axial field of view of 10.8 cm). PET image sets were obtained at rest and during performance of a stroop task. The colour of the presented word was identical with the written word (congruent) or did not match the written word (incongruent) in randomized order. Subjects were instructed to name the colour and not to read the presented word. Images were normalized, coregistered, resliced and stereotactically transformed as described previously by Minoshima et al. [1, 2]. Differences between the control and activation images were expressed as voxel-by-voxel t-statistic values using a pooled variance [3]. Clusters ofpixel exhibiting a Z-score above 3.1 in the control group were used to create 21 3D-templates for subsequent ROl-analysis using the unsmoothed stereotactically transformed substraction finages normalized to global cerebral activity. For comparison of patients and normal controls unpaired t-test was performed. Results:
21 regions defined by significant CBF increase during performance of the Stroop task in the control subjects were analyzed for CBF changes in Alzheimer subjects. Statistically significant differences were found in 2 regions. These regions showed a reduced cerebral blood flow already under resting conditions. In the right inferior parietal lobe a CBF flacrease of 17.4 • in normal subjects was contrasted by a drop of-5.02 • % in Alzheimer subjects. In the left superior temporal gyrus a 21.4% • rCBF increase in normal subects was seen as opposed to a -5.6 • 13.0 % decrease in Alzheimer patients. T-statistic maps didn't reveal any activation in the entire right parietal lobe in the AD-group. This contradicts the assumption that these findings are only based on minor differences in localization of activation foci between the groups. Table 1
Anatomical location
Volume of the 3D ROl
Tailarach coordinates
Inf. Parietal lobe R Sup. Temporal gyrus L
0.5 ml 0.2 ml
-44, -40, 43 64, -24, 14
mean rCBF changes in control 17.4i14.3 21.4•
mean rCBF changes in patients -5.02• -5.6•
p-value
=0.001 =0.001
Conclusions:
Brain activation differs significantly between normal subjects and patients with Alzheimer's disease. Our results indicate that in particular areas with reduced cerebral blood flow under resting conditions may be activated less under stimulated conditions. References
1. Minoshima S, Berger KL, Lee KS, Mintun MA. J Nucl Med 1992;33:1579-1585 2. Minoshima S, Koeppe RA, Mintun MA, Berger KL, Taylor SF, Frey KA, Kuhl DE. J Nucl Med 1993;34:322329 3. Worsley K J, Watson JD, Lueck CJ et al. J Cereb Blood Flow Metab 1992; 12:900-918 $520