Paula,

Cognitive decline and dementia in PD and AD are entirely two distinct entities with different biochemical profiles. NOT ONE of us should be offered an anti-dementia drug prescribed for AD patients!

Three things (well, four actually- see my fipamezole post in clinical trials; good news on this)

Neuropsychiatric differences between Parkinson's disease with dementia and Alzheimer's disease.
Int J Geriatr Psychiatry. 2001 Feb;16(2):184-91.
Aarsland D, Cummings JL, Larsen JP.

OBJECTIVE: To compare the profile of neuropsychiatric symptoms in patients with Parkinson's disease with dementia (PDD) and patients with Alzheimer's disease (AD)... CONCLUSIONS: Neuropsychiatric symptoms are common and severe in patients with PDD, with important implications for the management of these patients. AD and PDD patients have different neuropsychiatric profiles, suggesting different underlying mechanisms. Cognitive impairment, psychopathology, and motor features progress independently in PDD patients Copyright 2001 John Wiley & Sons, Ltd.

Brain metabolism differs in Alzheimer's disease and Parkinson's disease dementia.
Alzheimer's and Dementia, Volume 4, Issue 6, Pages 421-427
H. Griffith, J. den Hollander, et al.

Few comparative studies exist of metabolic brain changes among neurodegenerative illnesses. We compared brain metabolic abnormalities in Alzheimer's disease (AD) and in Parkinson's disease with dementia (PDD) as measured by proton magnetic resonance spectroscopy (MRS).
Methods

Twelve patients with idiopathic PDD, 22 patients with probable mild AD, and 61 healthy older controls underwent posterior cingulate MRS.
Results

Patients with AD exhibited reduced N-acetyl aspartate (NAA)/creatine (Cr) (P < .05) and increased choline (Cho)/Cr (P < .05) and myo-inositol (mI)/Cr (P < .01) compared with controls. Patients with PDD exhibited reduced NAA/Cr (P < .05) and glutamate (Glu)/Cr (P < .01) compared with controls. There was reduced Glu/Cr in PDD compared with AD (P < .01).
Conclusions

Patients with AD and patients with PDD exhibited distinct brain metabolic MRS profiles. Findings suggest that comparison of brain MRS profiles across dementias provides useful direction for future study.

READ this, please!


"Cholinesterase Inhibitors: Drugs Looking for a Disease?"