To evaluate the TCD blood flow hemodynamics of AD and compare with that of vascular dementia (VD) and normal control patients.

Transcranial Doppler (TCD) is a non-invasive and inexpensive method for cerebral hemodynamic assessment. The cerebral arteries in Alzheimer’s dementia (AD) are morphologically altered and dysfunctional than in controls possibly related to amyloid cascade hypothesis in AD.

Thirty AD patients were studied and compared with 30 VD patients and 30 age matched controls at the Institute of Neurology, Madras Medical College. Two values namely Pulsatility index (PI) and mean blood flow velocity (MBFV) in the middle cerebral artery (MCA) were studied. Patients satisfying probable NINDS-AIREN and NINCDS-ACRCA criteria for VD and AD respectively were included. Patients with significant carotid artery disease ,coronary artery disease with systolic failure and acute stroke were excluded.Statistical analysis was done using SPSS statistics software (v26).

The MCA MBFV in VD [37.5 ± 9.4, p< 0.05 (CI 95%)] and AD [38.3 ± 7.2, p<0.05 (CI95%) ] were significantly lower than in controls (51.4 ± 10.5) but did not vary significantly between AD and VD. Similarly, PI in VD [1.3 ± .2, p<0.05 (CI95%) ] and AD [1.09 ± .2, p< 0.05 (CI 95%] were significantly higher than in controls (.8 ± .2). Although MCA PI was higher in VD than AD this was not statistically significant (p >0.5).

In our study, although TCD did not help to distinguish between VD and AD, it showed vascular flow and resistance changes in AD similar to VD. The significance of vascular pathology in AD needs further research and evaluation.