title: Cognitive impairment and infectious burden in the elderly.
abstract: Infectious agents have been suspected as contributing factors to dementia, especially in Alzheimer disease. We intended to test whether viral or bacterial seropositivity is associated with cognitive impairment among home-dwelling elderly. Viral burden (seropositivity for herpes simplex type 1 (HSVI), type 2 (HSV2), or cytomegalovirus (CMV), and bacterial burden (Chlamydia pneumoniae and Mycoplasma pneumoniae) were tested among 383 home-dwelling individuals with vascular disease (mainly coronary heart disease) in the ongoing DEBATE study (mean age 80 years). Mini-mental state examination (MMSE) and its changes were used to define cognitive impairment. At baseline, 0-1, 2, and 3 positive titers toward viruses were found in 48 (12.5 %), 229 (59.8 %), and 106 (27.7 %) individuals,respectively. MMSE points decreased with increasing viral burden (p = 0.03). At baseline,58 individuals (15.1 %) had cognitive impairment (MMSE < 24 points) which after adjustments was significantly associated with seropositivity for 3 viruses (risk ratio 2.5, 95%confidence interval 1.3 to 4.7). MMSE score decreased in 150 cases (43%) during 12-month follow-up. After adjustment for MMSE score at baseline and with 0-1 seropositivities as reference (1.0), the risk ratios were 1.8 (95 % confidence interval 0.9 to 3.6) and 2.3 (95% confidence interval 1.1 to 5.0) for 2 and 3 seropositivities, respectively. No significant associations were observed between bacterial burden and cognition. Viral burden of herpes virus and cytomegalovirus was associated with cognitive impairment in home-dwelling elderly. The association may offer a preventable cause of cognitive decline.
authors.affiliation: Department of Medicine, Geriatric Clinic, and Department of Virology, University of Helsinki, FIN-00029 HUS, Helsinki, Finland. timo.strandberg@hus.fi
authors.forename: T E
authors.initials: TE
authors.lastname: Strandberg
authors.forename: K H
authors.initials: KH
authors.lastname: Pitkala
authors.forename: K
authors.initials: K
authors.lastname: Linnavuori
authors.forename: R S
authors.initials: RS
authors.lastname: Tilvis
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000453:epidemiology; D001424:Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology; D016993:Chlamydophila pneumoniae / Q000302:isolation & purification; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control*; D015897:Comorbidity; D017281:Cost of Illness; D006566:Herpesviridae Infections / Q000453:epidemiology / Q000821:virology; D006801:Humans; D009177:Mycoplasma pneumoniae / Q000302:isolation & purification; D009483:Neuropsychological Tests; D012720:Severity of Illness Index; D014777:Virus Diseases / Q000453:epidemiology* / Q000821:virology