Published on: January 29, 2013
by Charles Bankhead for MedPage Today:
Heart disease in older women tripled their likelihood of mild cognitive impairment, data from a large cohort study showed.
The association between heart disease and cognitive function was limited to the non-amnestic subtype of impairment, which involves cognitive domains other than memory. Among women with cardiac disease, the hazard ratio for non-amnestic mild cognitive impairment was 3.07 versus women without cardiac disease (95% CI, 1.58 to 5.99), according to Rosebud Roberts, MB, ChB, of the Mayo Clinic in Rochester, Minn., and co-authors.
In contrast, men with cardiac disease had a nonsignificant 1.16 hazard ratio compared with men who did not have cardiac disease (95% CI 0.68 to 1.99), they reported online in JAMA Neurology.
Men with heart disease also had an increased risk of mild cognitive impairment, but the association did not achieve statistical significance, the investigators found.
“Our findings support the hypothesis that non-amnestic mild cognitive impairment has a vascular etiology,” they wrote. “For women, the association of cardiac disease with non-amnestic mild cognitive impairment persisted after the exclusion of participants with a history of stroke and after adjustment for several confounders.
“The similar incidences of non-amnestic mild cognitive impairment for men with and without cardiac disease … suggest that factors besides cardiac disease (e.g., stroke) may account for this higher incidence in men without cardiac disease.”
After excluding participants with a history of stroke, the association between heart disease and non-amnestic mild cognitive impairment was no longer significant, suggesting stroke has a confounding effect, the researchers added.
Mild cognitive impairment represents a key diagnostic/prognostic threshold for dementia. Impairment associated with memory loss (amnestic) has been hypothesized as having a predilection toward progression to Alzheimer’s disease.
In contrast, non-amnestic mild cognitive impairment may preferentially progress to vascular and other types of dementia unrelated to Alzheimer’s disease, according to the authors’ background information.
Roberts and colleagues previously reported a cross-sectional association between coronary disease and mild cognitive impairment (Neurobiol Aging 2010; 31: 1894-1902). They extended the investigation with separate analyses of the association in men and women.
The study population comprised 2,719 adults 70 and older participating in a prospective cohort study. Each participant underwent an evaluation at baseline and every 15 months thereafter by means of the Clinical Dementia Rating Scale. After each evaluation, investigators reached a consensus diagnosis of normal cognition, mild cognitive impairment, or dementia.
Cardiac disease was determined by review of participants’ medical records.
The final analysis involved 1,450 participants who had neither mild cognitive impairment nor dementia at baseline. The study population comprised 722 men and 728 women. With respect to age distribution, 57.3% of men and 48.4% of women were 70 to 79, whereas 42.7% of men and 51.6% of women were 80 to 89 (P=0.001).
During a median follow-up of 4 years, 348 study participants developed mild cognitive impairment, defined as: concern expressed by participant, healthcare provider, or other informant; impairment in one of four cognitive domains assessed; normal functional activity; and absence of dementia. An additional 18 participants developed dementia.
The authors reported that 231 of the 348 participants with mild cognitive impairment had the amnestic subtype (154 single domain, 77 multiple domain), 93 participants had non-amnestic impairment (73 single domain, 20 multiple domain), and 24 participants had mild cognitive impairment of unknown subtype.
Of the subgroup with non-amnestic mild cognitive impairment, 87 participants had impaired executive function, 20 had impairment of visuospatial skills, and six had language impairment.
Overall, 669 (46.1%) of the participants had some form of cardiac disease, including 57.1% of men and 35.3% of women (P<0.001). The most common conditions were atrial fibrillation (18.0% of men and 11.3% of women, P<0.001), coronary artery disease (52.9% versus 28.4%, P<0.001), congestive heart failure (10.9% versus 9.8%, NS), and stroke (10.1% versus 8.9%, NS).
Participants with cardiac disease had a higher incidence of mild cognitive impairment than did those without cardiac disease (73.2 versus 62.1 per 1,000 person-years). Men with cardiac disease had a higher rate of mild cognitive impairment than did women with cardiac disease (75.7 versus 71.4 per 1,000 person-years).
Analysis of data by subtype of mild cognitive impairment showed no significant associations of cardiac disease with any type of mild cognitive impairment or with the amnestic subtype. The incidence of non-amnestic mild cognitive impairment was almost twice as high in participants with cardiac disease (23.4 versus 12.2 per 1,000 person-years).
Analysis by subtype and by sex showed that the incidence of non-amnestic mild cognitive impairment was similar in men with and without cardiac disease (23.4 versus 18.9 per 1,000 person-years). However, women with cardiac disease had an incidence of non-amnestic mild cognitive impairment of 24.3 per 1,000 person-years versus 7.4 per 1,000 person-years for women without cardiac disease.
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