[Cerebral hemodynamics in patients with dementia]

Area of Science:

• Neurology
• Radiology
• Gerontology

Background:

• Alzheimer's disease (DAT) and vascular dementia (VD) are leading causes of cognitive decline.
• Assessing cerebral blood flow (CBF) and autoregulation is crucial for understanding dementia pathophysiology.
• Current diagnostic methods may not always distinguish between DAT and VD effectively.

Purpose of the Study:

• To evaluate cerebral autoregulation in DAT and VD patients using SPECT imaging.
• To determine the diagnostic significance of resting CBF and a standing test in differentiating DAT and VD.
• To introduce and validate a novel dysautoregulation index (D.I.) for differential diagnosis.

Main Methods:

• Resting cerebral blood flow (CBF) measured using 123I-IMP SPECT.
• A standing test conducted using 99mTc-HMPAO SPECT to assess dynamic CBF changes.
• Comparison of CBF parameters and a calculated dysautoregulation index (D.I.) between DAT, VD, and healthy control groups.

Main Results:

• Both DAT and VD groups showed significantly reduced resting CBF compared to controls.
• DAT patients had lower parietal CBF than VD patients; CBF correlated with dementia scores in DAT.
• Vascular dementia patients exhibited a significantly greater decrease in CBF during the standing test, resulting in a higher D.I. compared to DAT and controls.

Conclusions:

• Resting CBF is diminished in both DAT and VD, but regional differences exist.
• The dysautoregulation index (D.I.) effectively differentiates VD from DAT, likely due to impaired cerebral autoregulation in VD.
• D.I. provides valuable diagnostic information beyond resting CBF, aiding in the differential diagnosis of dementia.