Five-year follow-up of 11C-PIB uptake in Alzheimer's disease and MCI.
OBJECTIVE
The aim of this study was to evaluate the longitudinal changes in [(11)C]PIB uptake in mild cognitive impairment (MCI) and Alzheimer's disease (AD) over a long-term follow-up.


METHODS
Six AD patients, ten MCI patients and eight healthy subjects underwent a [(11)C]PIB PET scan at baseline and at 2 and 5 years. The clinical status of the MCI patients was evaluated every 6 months.


RESULTS
The MCI group showed a significant increase in [(11)C]PIB uptake over time (p < 0.001), with a similar increase from baseline to 2 years (4.7% per year) and from 2 to 5 years (5.0% per year). Eight MCI patients (80%) converted to AD, and two of these patients showed a normal [(11)C]PIB scan at baseline but increased uptake later. There was an increase in [(11)C]PIB uptake with time in the AD group (p = 0.02), but this did not significantly differ from the change in the control group.


CONCLUSIONS
Our results revealed a significant increase in amyloid load even at the time of AD diagnosis in some of the MCI patients who converted. A positive [(11)C]PIB scan at baseline in MCI patients strongly predicted future conversion to AD but a negative PIB scan in MCI patients did not exclude future conversion. The results suggest that there is wide individual variation in the brain amyloid load in MCI, and in the course of amyloid accumulation in relation to the clinical diagnosis of AD.
Turku PET Centre, University of Turku, P.O. Box 52, 20521, Turku, Finland, nina.kemppainen@tyks.fi.
N M
NM
Kemppainen
N M
NM
Scheinin
J
J
Koivunen
J
J
Johansson
J T
JT
Toivonen
K
K
Någren
J
J
Rokka
M
M
Karrasch
R
R
Parkkola
J O
JO
Rinne
D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis / Q000000981:diagnostic imaging*; D000814:Aniline Compounds; D052160:Benzothiazoles; D016022:Case-Control Studies; D060825:Cognitive Dysfunction / Q000175:diagnosis / Q000000981:diagnostic imaging*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D013844:Thiazoles
C475519:2-(4'-(methylamino)phenyl)-6-hydroxybenzothiazole; D000814:Aniline Compounds; D052160:Benzothiazoles; D019275:Radiopharmaceuticals; D013844:Thiazoles