Dr. Ron’s Research Review – May 11, 2011

This week’s research review focuses on Alzheimer’s disease and CAD.

Vascular risk factors promote conversion from mild cognitive impairment to Alzheimer disease

            (Li, Wang et al. 2011)

Coronary blood flow in patients with stable coronary artery disease treated long term with folic acid and vitamin B12

            (Bleie, Strand et al. 2011)

Long-term treatment with a combination of folic acid and vitamin B12 increase basal and adenosine-induced maximal coronary blood flow.

Dr. Ron


Articles

Coronary blood flow in patients with stable coronary artery disease treated long term with folic acid and vitamin B12

            (Bleie, Strand et al. 2011) Download

BACKGROUND: Plasma concentration of total homocysteine is associated with risk of cardiovascular disease in epidemiological studies. We wanted to examine the effects of B-vitamin therapy, which may lower total homocysteine, on coronary flow and vascular function in patients with established coronary artery disease (CAD). METHODS: Forty patients with stable CAD, mean (standard deviation) aged 57.8 (9.0) years, recruited into the Western Norway B-Vitamin Intervention Trial, were randomly assigned to daily oral treatment with 0.8 mg of folic acid and 0.4 mg of vitamin B12 or placebo, and 40 mg of vitamin B6 or placebo, using a 2x2 factorial design. At baseline, and after 9 and 24 months, coronary blood flow was assessed by coronary angiography and Doppler flow-wire measurements during intracoronary infusion of saline (basal), incremental doses of acetylcholine, adenosine, and nitroglycerin. RESULTS: We found a significant increase in basal (P<0.02) and adenosine-induced (P<0.05) coronary blood flow in patients who received folic acid/vitamin B12 for 24 months, compared with placebo or vitamin B6 alone. Folic acid/vitamin B12 or vitamin B6 treatment did not change endothelial-dependent response after acetylcholine infusion or flow-dependent proximal dilatation in response to adenosine-induced maximal hyperemia (P>/=0.45). CONCLUSION: Long-term treatment with a combination of folic acid and vitamin B12 increase basal and adenosine-induced maximal coronary blood flow. This may reflect improved microvascular function in patients with stable CAD.

Vascular risk factors promote conversion from mild cognitive impairment to Alzheimer disease

            (Li, Wang et al. 2011) Download

OBJECTIVE: Growing evidence suggests that vascular risk factors (VRF) contribute to cognitive decline. The aim of this study was to investigate the impact of VRF on the conversion from mild cognitive impairment (MCI) to Alzheimer disease (AD) dementia. METHODS: A total of 837 subjects with MCI were enrolled at baseline and followed up annually for 5 years. The incidence of AD dementia was investigated. A mixed random effects regression model was used to analyze the association between VRF and the progression of MCI assessed with Mini-Mental State Examination and instrumental Activities of Daily Living. Cox proportional hazard models were used to identify the association between VRF and dementia conversion, and to examine whether treatment of VRF can prevent dementia conversion. RESULTS: At the end of the follow-up, 298 subjects converted to AD dementia, while 352 remained MCI. Subjects with VRF had a faster progression in cognition and function relative to subjects without. VRF including hypertension, diabetes, cerebrovascular diseases, and hypercholesterolemia increased the risk of dementia conversion. Those subjects with MCI in whom all VRF were treated had a lower risk of dementia than those who had some VRF treated. Treatment of individual VRF including hypertension, diabetes, and hypercholesterolemia was associated with the reduced risk of AD conversion. CONCLUSION: VRF increased the risk of incident AD dementia. Treatment of VRF was associated with a reduced risk of incident AD dementia. Although our findings are observational, they suggest active intervention for VRF might reduce progression in MCI to AD dementia.

References

Bleie, O., E. Strand, et al. (2011). "Coronary blood flow in patients with stable coronary artery disease treated long term with folic acid and vitamin B12." Coron Artery Dis.

Li, J., Y. J. Wang, et al. (2011). "Vascular risk factors promote conversion from mild cognitive impairment to Alzheimer disease." Neurology 76(17): 1485-1491.