Different TMS patterns of intracortical inhibition in early onset Alzheimer dementia and frontotemporal dementia.
OBJECTIVE
To investigate putative changes in cortical excitability of patients affected by early-onset mild dementia by means of transcranial magnetic stimulation (TMS) and to verify whether a peculiar neurophysiological profile may contribute to characterise Alzheimer's disease (AD) vs frontotemporal dementia (FTD).


METHODS
Motor threshold and intracortical inhibition (ICI) and facilitation (ICF) after paired-pulse TMS (inter-stimulus intervals from 1 to 20 ms) were studied in two groups of early-onset demented patients with a neuropsychological profile suggestive of AD (n = 12) and FTD (n = 8). Twelve age-matched healthy subjects were considered as control group. In both patient groups, recordings were performed before and after a single oral dose of 4 mg galantamine.


RESULTS
No significant difference in motor threshold was observed among the three studied groups. On the contrary, early-onset AD showed a significant reduction of ICI compared to control group, no changes were detected in FTD patients. No significant changes in ICF were found between both patient groups and healthy subjects. The acute administration of galantamine reversed the modified ICI in AD group.


CONCLUSIONS
The differential pattern of ICI exhibited by early-onset AD vs FTD in the early stage of disease may represent a non-invasive, reproducible electrophysiological tool, which may contribute to early differential diagnosis and, possibly, to monitor therapeutic effectiveness.


CONCLUSIONS
The present results support the possibility that subtle, early modifications in intracortical circuitry features AD, but not FTD patients.
Pierantozzi
M
M
IRCCS Fondazione Santa Lucia, Via Ardeatina 306, 00173 Rome, Italy.
Panella
M
M
Palmieri
M G
MG
Koch
G
G
Giordano
A
A
Marciani
M G
MG
Bernardi
G
G
Stanzione
P
P
Stefani
A
A
D000368:Aged; D000544:Alzheimer Disease / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology* / Q000528:radiation effects*; D002800:Cholinesterase Inhibitors / Q000493:pharmacokinetics; D003704:Dementia / Q000503:physiopathology*; D004574:Electromagnetic Fields; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D007839:Functional Laterality / Q000502:physiology; D005702:Galantamine / Q000493:pharmacokinetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D018696:Neuroprotective Agents / Q000493:pharmacokinetics; D013702:Temporal Lobe / Q000503:physiopathology*
D002800:Cholinesterase Inhibitors; D018696:Neuroprotective Agents; D005702:Galantamine