Combined cerebral blood flow effects of a cholinergic agonist (milameline) and a verbal recognition task in early Alzheimer's disease.
RU 35926/CI-979 (milameline) is a partial muscarinic agonist with promnestic effects in animal models. Preliminary animal studies suggest that this agent has the capacity to reverse cholinergic dysfunction and that it may impact on regional cerebral blood flow (rCBF). A total of 10 subjects with Alzheimer's disease (AD) of mild severity underwent high resolution split-dose single photon emission computed tomography (SPECT) during performance of a verbal recognition and control task, both before and after 18 weeks treatment with melameline or placebo. SPECT images were coregistered with individual's magnetic resonance imaging scans allowing extraction of rCBF values from multiple anatomical regions of interest (ROI). The effect of milameline was examined in eight individuals who were found after unblinding to be taking active drug. Effects of milameline were most apparent in the frontal regions, basal ganglia and thalamus. In the group as a whole, the greatest increase in rCBF due to milameline treatment was observed in the left globus pallidus. Response to milameline treatment was associated with increases in rCBF in the cingulate gyrus bilaterally, and less so for the left thalamus. Milameline-related increases in rCBF values were exaggerated by the verbal recognition task. Milameline has a demonstrable effect on cerebral blood flow in mild AD. Consistent with emerging animal data, the effects on rCBF appear most prominent in frontal and subcortical regions in AD subjects. The effects on rCBF appear to be augmented by the performance of a cognitively demanding task, raising the possibility that such tasks could assist in building an awareness of the functional neuropsychopharmacology of drugs designed for cognitive enhancement.
Trollor
Julian N
JN
School of Psychiatry, University of New South Wales, Sydney, Australia. j.trollor@unsw.edu.au
Sachdev
Perminder S
PS
Haindl
Walter
W
Brodaty
Henry
H
Wen
Wei
W
Walker
Brenda M
BM
D000544:Alzheimer Disease / Q000188:drug therapy* / Q000503:physiopathology / Q000523:psychology; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D004095:Dihydropyridines / Q000627:therapeutic use*; D004311:Double-Blind Method; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D018721:Muscarinic Agonists / Q000627:therapeutic use*; D009483:Neuropsychological Tests; D010091:Oximes / Q000627:therapeutic use*; D017397:Prefrontal Cortex / Q000098:blood supply / Q000187:drug effects; D011597:Psychomotor Performance / Q000187:drug effects; D021641:Recognition, Psychology / Q000187:drug effects*; D015899:Tomography, Emission-Computed, Single-Photon
D004095:Dihydropyridines; D018721:Muscarinic Agonists; D010091:Oximes; C084978:milameline