Dementia: clinical-neurobiochemical correlations

ABSTRACT

This study aimed at correlating the cognitive impairments and their neuropathological basis in AD and VaD with the neurobiochemical changes in brain tissues using proton magnetic resonance spectroscopy [[1]H-MRS]. Twenty patients diagnosed as having dementia [10 with AD, and 10 with VaD] were included in this study and compared with 10 normal control subjects. Dementia patients were selected using DSM IVR, HIS, ADDTC and NINCDS. Patients were submitted to the following battery of investigations Thorough clinical examination, routine Laboratory investigations, and various neuropsychological scales [MMSE, CAMCOG, Blessed DR scale, and Hamilton depression scale]. Brain MRI and MRS were done for all patients and control subjects. Cognitive impairment was significantly more prominent in AD patients compared to VaD patients. The most consistent neurochemical differences between demented patients and normal control subjects were significant reductions of the NAA/Cr and NAA/MI ratios at PCG and NAA/Cr ratio at Lt STG, and elevation of MI/Cr ratio at PCG, while the most consistent differences between AD and VaD patients were significant reductions of the NAA/Cr and NAA/MI ratios at PCG, Lt STG and elevated MI/Cr ratio at PCG in patients with A.D. Significant correlation was observed between the reduced NAA/Cr, NAA/MI and elevated MI/Cr ratio at PCG and changes in various neuropsychological variables studied in AD patients. Clinical neuropsychological testing is a fairly good tool for differentiation of the types of dementia [AD versus VaD]. However the neurochemical changes in brain tissues measured using [[1]H-MRS] are useful not only in distinguishing between dementia of the Alzheimer's type and vascular dementia but also explaining their neuropathological background: