The second report from the Alzheimer's Disease Cholesterol-Lowering Treatment (ADCLT) trial was recently published, along with several reviews of clinical and laboratory investigations of the statins, in a theme issue of Acta Neurologica Scandinavica. The accumulated data reflect the potential of the agents to affect the onset or course of Alzheimer disease (AD), with contradictory or insufficient evidence of treatment effect.
The first ADCLT report suggested that lowering cholesterol levels with atorvastatin (Lipitor) could reduce cognitive and behavioral deterioration in persons with mild to moderate AD.1 This second report examined whether the apparent benefit is influenced by severity of cognitive impairment, circulating cholesterol levels, or apolipoprotein E genotype.2
The ADCLT trial is a double-blind controlled study involving 67 patients with mild to moderate AD, randomized to receive 1 year of treatment with atorvastatin (80 mg/d) or placebo. The primary measure is scoring on the Alzheimer's Disease Assessment Scale–Cognitive (ADAS-cog) subscale, with secondary measurement on the Mini-Mental State Examination (MMSE). Prestudy medications for both AD and comorbidities continued throughout the study period.
Both the statin treatment and placebo groups showed deterioration on the ADAS-cog at 3 months, and the placebo group continued to deteriorate by about 1 point per quarter throughout the study period. The ADAS-cog mean score in the statin treatment group was about 3.5 points higher than the mean score of the placebo group at 6 months. The ADCLT investigators reported that the benefit of the statins appeared to be more prominent in those with cholesterol levels above 200 mg/dL, those with the apoE4 allele, and those with higher baseline MMSE scores.
In regard to the latter patient group (those with higher baseline MMSE scores), the investigators commented, “This is consistent with evolving opinion that the earlier the treatment of AD, the better the outcome, and the concept of treating the disorder, clinically presenting as mild cognitive impairment, in advance of transition to clinical impairment consistent with AD.”2
In one of the accompanying commentaries, Kivipelto and colleagues3 note that while most discussion of the cause of AD has centered on the genes and protein patterns in familial-linked onset, most AD emerges sporadically, outside of familial patterns, and presents considerable heterogeneity of risk factors, pathogenesis, and neuropathologic processes.
“In this markedly multifactorial sporadic AD, the involvement of lipids from both plasma and brain should not be underestimated,” they indicate. “It took several decades for data on peripheral lipid metabolism to emerge, and it will again take time to elucidate brain lipid metabolism and the interaction between the two lipid pools.”3
1. Sparks DL, Sabbagh MN, Connor DJ, et al. Atorvastatin for the treatment of mild-to-moderate Alzheimer's disease: preliminary results: Arch Neurol. 2005;62:753- 757.
2. Sparks DL, Connor DJ, Sabbagh MN, et al. Circulating cholesterol levels, apolipoprotein E genotype and dementia severity influence the benefit of atorvastatin treatment in Alzheimer's disease: results of the Alzheimer's Disease Cholesterol-Lowering Treatment (ADCLT) trial. Acta Neurol Scand. 2006;114(suppl 185):3-7.
3. Kivipelto M, Solomon A, Winblad B. Alzheimer's disease: back to the future. Acta Neurol Scand. 2006;114 (suppl 185):119-120.
4. Rockwood K. Epidemiological and clinical trials evidence about a preventative role for statins in Alzheimer's disease. Acta Neurol Scand. 2006;114(suppl 185):71-77.
5. Wolozin B, Manger J, Bryant R, et al. Re-assessing the relationship between cholesterol, statins and Alzheimer's disease. Acta Neurol Scand. 2006;114(suppl 185):63-70.
6. Sparks DL. Coronary artery disease, hypertension, ApoE, and cholesterol: a link to Alzheimer's disease? Ann NY Acad Sci. 1997;826:128-146.
7. Höglund K, Wallen A, Blenow K. Effect of statins on ß-amyloid metabolism in humans: potential importance for the development of senile plaques in Alzheimer's disease. Acta Neurol Scand. 2006;114(suppl 185):87-92.
8. Park IH, Hwang EM, Hong HS, et al. Lovastatin enhances Abeta production and senile plaque deposition in female Tg2576 mice. Neurobiol Aging. 2003;24:637-643.
9. Ishii K, Tokuda T, Matsushima T, et al. Pravastatin at 10 mg/day does not decrease plasma levels of either amyloid-beta (Abeta) 40 or Abeta 42 in humans. Neurosci Lett. 2003;350:161-164.
10. Sparks DL, Sabbagh MN, Connor DJ, et al. Statin therapy in Alzheimer's disease. Acta Neurol Scand. 2006;114(suppl 185):78-86.
11. Crisby M. The role of pleiotropic effects of statins in dementia. Acta Neurol Scand. 2006;114(suppl 185):115-118.