Single SPECT measures of cerebral cortical perfusion reflect time-index estimation of dementia severity in Alzheimer's disease.
To determine the relationship between cerebral cortical blood flow loss and the temporal development of the dementia in Alzheimer's disease (AD), SPECT was studied in a cross section of AD patients with a broad range of impairment.


METHODS
Thirty patients with a diagnosis of probable AD had their mini-mental state examination scores transformed into time-index values to give an estimation of dementia severity relative to the developmental time course. SPECT images were obtained using 99mTc-ethyl cysteinate dimer and a 3-head camera. Cortical surface perfusion was analyzed, including modified Talairach standardization, to obtain cortical elements from the convexity (each representing about 0.25 cm2 at the surface, 6.6-mm cortical depth) referenced to the mean perfusion of the full greater cerebellar hemisphere. These element ratios were analyzed (individually and by averages of estimated Brodmann's areas and brain regions) using linear regression with the time-index value.


RESULTS
For individual posterotemporal and inferoparietal Brodmann's areas (21, 22 and 39, 40, respectively) the correlation coefficients between cortical perfusion ratios and dementia severity ranged between -0.67 and -0.78 (P < 0.001). Perfusion ratios from these regions declined 2.5%-4.2% for each estimated year of progression. Prefrontal area perfusion showed less association with severity. Perfusion in primary cortical regions had no significant association with dementia severity.


CONCLUSIONS
Cerebral cortical perfusion loss is temporally related to development of dementia. The spatial pattern of high, significant correlations between cortical perfusion and dementia severity shows a regional distribution that corresponds closely to the distribution of AD pathology described in autopsy studies.
Ashford
J W
JW
Department of Psychiatry, Alzheimer's Disease Research Center of the National Institute on Aging, College of Medicine, University of Kentucky, Lexington 40509, USA.
Shih
W J
WJ
Coupal
J
J
Shetty
R
R
Schneider
A
A
Cool
C
C
Aleem
A
A
Kiefer
V H
VH
Mendiondo
M S
MS
Schmitt
F A
FA
D000368:Aged; D000544:Alzheimer Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D001921:Brain / Q000000981:diagnostic imaging*; D002560:Cerebrovascular Circulation / Q000502:physiology; D003545:Cysteine / Q000031:analogs & derivatives; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008609:Mental Status Schedule; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D012720:Severity of Illness Index; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon
D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C059659:technetium Tc 99m bicisate; D003545:Cysteine