ICAD: Marriage May Protect Against Dementia

By Todd Neale

CHICAGO, 31 july 2008-- The give and take of marriage may be enough to stave off Alzheimer's disease and other cognitive impairment, a prospective population-based study suggested. People living alone from midlife on were almost three times as likely to develop some level of cognitive impairment as those who were living with a partner (OR 2.89, P<0.001).
Krister Hakansson, of Vaxjo University in Vaxjo, Sweden, and the Karolinska Institute in Stockholm, reported at the International Conference on Alzheimer's Disease here. There were similar greater risks of mild cognitive impairment (OR 3.17, P<0.001) and Alzheimer's disease (OR 2.83, P<0.05) for those living alone.
"This study points to the beneficial effects of a married life," Hakansson said, "consistent with the general hypothesis of social stimulation as a protective factor against dementia."
It has been suggested that remaining socially active may protect against the development of dementia, and Hakansson reasoned that a partner relationship would form the most intense form of social interaction because of the necessity of dealing with another's needs or perspectives, enhanced communication, and joint problem-solving.
So he and colleagues turned to the Cardiovascular Risk Factors, Aging, and Dementia (CAIDE) study, which randomly selected middle-age participants from the general population of Finland. Baseline measurements were taken from 1972 to 1987.
In 1998, after a mean follow-up of 21 years, 1,432 of the participants ages 65 to 79 were evaluated for signs of cognitive impairment. At baseline, 1,147 were married or cohabitating, 111 were single, 63 were separated or divorced, and 111 were widowed.
At the end of follow-up, 139 were diagnosed with some form of cognitive impairment, including 82 with mild cognitive impairment -- which may represent a transitional phase between normal age-related memory decline and Alzheimer's disease -- and 48 with Alzheimer's.
Those who were not living with a partner at midlife were twice as likely to have some level of cognitive impairment (OR 2.09, P<0.01) or mild cognitive impairment (OR 2.14, P<0.01) later in life than those who were married or cohabitating, regardless of their late-life living status.
The association with an increased risk of Alzheimer's disease did not reach statistical significance.
Widowed participants at midlife who did not remarry had the highest increased risk of any cognitive impairment (OR 3.53, P<0.001), mild cognitive impairment (OR 3.10, P<0.01), and Alzheimer's disease (OR 7.70, P<0.001) later in life.
Having the APOE-e4 genotype -- a risk factor for Alzheimer's -- was particularly damaging for those who were widowed or divorced from midlife through late life. Those who were married and had the high-risk genotype had a 3.44-fold (P<0.05) increased risk of Alzheimer's disease, compared with a 25.55-fold (P<0.001) greater risk for those who were divorced or widowed.
This suggested, Hakansson said, that other factors beyond cohabitation were involved in the associations.
All analyses were adjusted for education, body mass index, cholesterol, blood pressure, occupation, physical activity, smoking habits, and depression at midlife, as well as APOE e4 status, age at follow-up, and gender.
Hakansson speculated that those who were widowed or divorced -- and remained so -- were at a greater risk than those who were single because the loss of a partner destabilized the psychobiological system, enhancing vulnerability to disease.
Hakansson made no disclosures.
Primary source: International Conference on Alzheimer's DiseaseSource reference:Hakansson K "Unmarried life: paving the way for dementia?" ICAD 2008; Abstract O2-07-01.