Vascular dementia: from clinical to biochemical and neurophysiological markers

BACKGROUND: Vascular Dementia can be considered the second most common cause of dementia after Alzheimer s disease. However, unlike the degenerative dementias, it s possible to carry out preventive strategies. Recently, neurophysiological techniques and in particular transcranial magnetic stimulation (TMS), have been tested in patients with dementia in order to pick up early cerebral functional changes. The present research aimed to investigate cortical excitability in elderly patients with leukoaraiosis METHODS: Motor cortex excitability, intracortical inhibition and facilitation circuits and central cholinergic function were evaluated in patients with a clinical features of vascular cognitive impairment-no dementia. The neuropsychological profile and the vascular burden at brain magnetic resonance imaging were concomitantly explored. RESULTS: No differences were found for measures of motor cortex excitability between patients and controls. A significant enhancement of intracortical facilitation was observed in patients. Moreover central cholinergic circuits seem to be spared in patients. DISCUSSION AND CONCLUSION: This study provides the first evidence of functional changes in intracortical excitatory neuronal circuits in patients with vascular cognitive impairment-no dementia, a finding which is in line with previous research on vascular dementia. Central cholinergic functioning seems to be spared in patients. This functional integrity differs from that reported in patients with Alzheimer s disease or mild cognitive impairment, underlying the distinctive involvement of the cholinergic pathway in degenerative dementia and vascular form, even in their early or preclinical stage. The non-invasive evaluation of the pathophysiological and neurochemical mechanisms underlying dementia highlights the emerging role of TMS as a powerful tool in the diagnosis and management of different dementing processes