Lack of association between vascular dementia and Chlamydia pneumoniae infection: a case-control study.

BACKGROUND: Chronic inflammation appears to play a role in the pathogenesis of vascular dementia. Given the association between Chlamydia pneumoniae and stroke, the possibility exists that previous exposure to C. pneumoniae may play a role in vascular dementia. The objective of this study was to determine if there was an association between serological evidence of C. pneumoniae infection or inflammatory markers with vascular dementia. METHODS: 28 case-patients with vascular dementia at a geriatric clinic and 24 caregiver-controls were tested for C. pneumoniae IgG and IgA antibodies. The association between vascular dementia and C. pneumoniae titres as well as inflammatory markers was estimated by using both conditional logistic regression and stratified logistic regression. RESULTS: When matched cases were compared to controls, there was no significant difference in elevated C. pneumoniae specific IgG antibodies (titre >or= 1:32), odds ratio [OR] 1.3 (95% confidence intervals [CI] 0.3 to 6.0), p = 0.71, or in elevated C. pneumoniae specific IgA antibodies (titre >or= 1:16), OR 2.0 (95%CI 0.5 to 8.0), p = 0.33 indicative of past or persistent C. pneumoniae infection. Similarly, no difference in high IgG or IgA antibody levels (IgG titre >or= 1:512 or IgA titre >or= 1:64) between the two groups, indicative of recent C. pneumoniae infection, was found, OR 0.4 (95%CI 0.1 to 2.1), p = 0.27. For C-reactive protein (CRP), the mean difference between 18 matched pairs (case - control) was - 3.33 mg/L. There was no significant difference between cases and controls when comparing log transformed values, OR 0.03 (95%CI 0.00 to 2.89), p = 0.13 or comparing CRP values above or below the median, OR 0.8 (95%CI 0.2 to 3.4), p = 0.71. For fibrinogen, the mean difference between pairs (case - control) was -0.07 g/L. There was no statistical difference between cases and controls when comparing log transformed values, OR 0.6 (95%CI 0.0 to 31.2), p = 0.79 or between fibrinogen values above and below the median, OR = 0.5 (95%CI 0.1 to 2.0), p = 0.50. CONCLUSION: We found no evidence for a significant association between C. pneumoniae infection, inflammatory markers such as CRP and fibrinogen, and vascular dementia.

A randomized, controlled trial of doxycycline and rifampin for patients with Alzheimer's disease.

OBJECTIVES: To assess whether doxycycline and rifampin have a therapeutic role in patients with Alzheimer's disease (AD). DESIGN: Randomized, triple-blind, controlled trial. SETTING: Three tertiary care and two community geriatric clinics in Canada. PARTICIPANTS: One hundred one patients with probable AD and mild to moderate dementia. INTERVENTION: Oral daily doses of doxycycline 200 mg and rifampin 300 mg for 3 months. MEASUREMENTS: The primary outcome was a change in Standardized Alzheimer's Disease Assessment Scale cognitive subscale (SADAScog) at 6 months. Secondary outcomes were changes in the SADAScog at 12 months and tests of dysfunctional behavior, depression, and functional status. RESULTS: There was significantly less decline in the SADAScog score at 6 months in the antibiotic group than in the placebo group, (-2.75 points, 95% confidence interval (CI)=-5.28 to -0.22, P=.034). At 12 months, the difference between groups in the SADAScog was -4.31 points (95% CI=-9.17-0.56, P=.079). The antibiotic group showed significantly less dysfunctional behavior at 3 months. There was no significant difference in adverse events between groups (P=.34). There were no differences in Chlamydia pneumoniae detection using polymerase chain reaction or antibodies (immunoglobulin (Ig)G or IgA) between groups. CONCLUSION: Therapy with doxycycline and rifampin may have a therapeutic role in patients with mild to moderate AD. The mechanism is unlikely to be due to their effect on C. pneumoniae. More research is needed to investigate these agents.