Researchers in Sweden found that people who have the APOE Alzheimer’s gene and who live alone in middle age after being widowed or separated from a life partner, are at higher risk of developing dementia.

The study is the work of Dr Krister Hakannson, a research fellow at the Karolinska Institute in Stockholm, and colleagues, and is published in the 2 July online issue of the BMJ.

Hakannson and colleagues set out to discover if having a life partner in mid life was linked to cognitive function later in life.

For the study they used data from random population samples from nearly 1,500 people in Finland that was taken at 5 year intervals starting in 1972 and up to 1987.

73 per cent of the participants were then examined again in 1998 when they were aged between 65 and 79, for signs of Alzheimer’s disease and mild cognitive impairment.

The results showed that:

  • Participants living with a partner in mid life (mean age 50.4), were less likely than single, separated or widowed participants, to show cognitive impairment in later life (at age 65 to 79).
  • Those widowed or divorced in mid life and still without a life partner at follow up, had three times the risk compared with those who were married or cohabiting.
  • Those widowed both at mid life and later life had over 7 times the chance (odds ratio 7.67, ranging from 1.6 to 40.0) for Alzheimer’s disease compared with married or cohabiting people.
  • But the highest increased risk was in those those participants who carried the apolipoprotein E (APOE) gene and who had lost their partner in mid life and were still without a life partner at follow up.
  • Adjusting for several potential confounders from mid life had little effect on the results.

The authors concluded that:

“Living in a relationship with a partner might imply cognitive and social challenges that have a protective effect against cognitive impairment later in life, consistent with the brain reserve hypothesis.”

However, they added that:

“The specific increased risk for widowed and divorced people compared with single people indicates that other factors are needed to explain parts of the results.”

But a combination of social as well as genetic factors might explain the dramatic increase in risk of getting Alzheimer’s for carriers of the APOE gene who remain widowed for a long time after losing their life partner in mid life, they said.

“Association between mid-life marital status and cognitive function in later life: population based cohort study.”
Krister Hakansson, Suvi Rovio, Eeva-Liisa Helkala, Anna-Riitta Vilska, Bengt Winblad, Hilkka Soininen, Aulikki Nissinen, professor, Abdul H Mohammed, Miia Kivipelto.
BMJ Published online 2 July 2009.

Source: BMJ.

Written by: Catharine Paddock, PhD