Abstract and Introduction
Abstract
The aim of this study was to investigate the associations between loss of a life partner and the development of dementia and decline in cognitive function in later life. We used an Icelandic cohort of 4,370 participants in the Age, Gene/Environment Susceptibility-Reykjavik Study who were living as married in 1978 (born in 1907–1935) and were either still married (unexposed cohort) or widowed (exposed cohort) at follow-up (in 2002–2006). We ascertained history of marital status and spouse's death by record linkage to the Registry of the Total Population, Statistics Iceland. The outcome measures were as follows: 1) dementia and mild cognitive impairment; and 2) memory, speed of processing, and executive function. During the observation period, 3,007 individuals remained married and 1,363 lost a spouse through death. We did not find any significant associations between loss of a spouse and our outcome variables, except that widowed women had poorer executive function (mean = −0.08) during the first 2 years after their husbands' deaths compared with still-married women (mean = 0.09). Our findings do not support the notion that the risk of dementia is increased following the loss of a spouse, yet women demonstrate a seemingly temporary decline in executive function following the death of a partner.
Introduction
Neurodegenerative disorders leading to cognitive impairment have become one of the largest public health threats of modern times. Although risk factors remain to a large extent unknown, a growing body of research, both in animal models and in humans, suggests an impact of psychological stress on cognitive impairment. Studies incorporating various measures of psychological distress and psychiatric disorders have reported an association with cognitive decline in older adulthood.
Loss of a spouse has been classified as one of the most stressful events a person can encounter. Indeed, widowed individuals have been shown to be at increased risk for psychological morbidity and higher overall mortality compared with married individuals. Animal models suggest that the introduction of a stressful environment impairs an animal's problem-solving skills and reduces the volumes of important memory structures, such as the hippocampus. Proposed mechanisms between stressful life events, such as bereavement, and cognitive decline in humans have accordingly been suggested to include hippocampal atrophy from stress-induced glucocorticoid secretion fueled by emotional trauma, as well as increased vulnerability to stress from diminished social support and interactions. Yet relatively few studies have specifically investigated the association between marital status change and cognitive decline. Some have found increased risk of cognitive decline in widowhood, whereas others have not. In a recent population-based cohort study, Håkansson et al. monitored changes in marital status and cognitive function in 1,449 Finns followed for an average of 21 years. They reported a markedly increased risk of cognitive impairment and Alzheimer's disease among those widowed in midlife and at follow-up compared with those who lived with a partner during the time period. With the detailed information on dementia and cognitive function from the Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study and complete ascertainment of marital status since 1978, we wanted to replicate the study by Håkansson et al. in another setting. In contrast to previous attempts, the available registry information on the actual timing of spousal loss allowed us to explore the relationship between timing from the stressful life event and the risk of cognitive impairment. Our overarching aim was, therefore, to investigate the associations between loss of a life partner and the risk of dementia and decline in cognitive function.