Mild cognitive impairment and quality of life in the oldest old: a closer look

Age-related cognitive decline is a widespread phenomenon, and there is an adjusted overall prevalence of 16% (effect size, 95% CI 12–20%), increasing with age, for mild cognitive impairment (MCI) [10]. In the light of demographic change and an aging society, cases of MCI are likely to rise. It is therefore crucial to understand the subjective implications of MCI for those affected. In the long run, this will help to develop suitable interventions and support.

Quality of life (QOL) is a key concept for understanding the subjective dimension of MCI and the impact it has on those affected. Most researchers agree on a multidimensional concept including physical, psychological, and social aspects as well as those related to daily life activities [6, 25]. In addition, over the lifespan, different aspects become relevant for QOL. Since our interest is in the oldest old, we assessed QOL with the WHOQOL-OLD, an instrument that specifically addresses domains that are relevant for individuals older than 60 years [4]: (1) sensory impairments and in how far they affect daily life as well as the ability to communicate with others (sensory abilities); (2) the amount of autonomy, independent decision taking, and ability to influence one’s future (autonomy); (3) received appreciation and felt satisfaction for accomplishments in life as well as a general future outlook (past, present, and future activities); (4) level of activity and possibilities to participate (social participation); (5) fears and attitudes related to death and dying (death and dying); and (6) possibilities to experience love and affection (intimacy).

Research comparing quality of life (QOL) of individuals with and without MCI is rare and inconsistent. While some studies report no difference between the two groups [19, 23], others report lower QOL for people diagnosed with MCI in almost all areas [28, 31]. Especially individuals who are aware of their MCI diagnosis seem to have reduced QOL independent of impairment severity [27]. Unfortunately, most studies refer to highly selective samples from memory clinics or nursing homes [19] or are focused on health-related QOL [14, 17, 22]. Only few studies are representative for the general population [15]. In addition, research on MCI is often centered around the idea of MCI as a risk factor for subsequent dementia, rather than on the direct effects of MCI on the individuals [2, 24, 34].

In this study, we want to investigate how MCI is associated with QOL. We will therefore (1) analyze the differences between individuals with and without MCI diagnosis in QOL in general and with regard to all six facets of QOL, i.e., sensory abilities; autonomy; past, present, and future activities; social participation; fears related to death and dying; and intimacy, and (2) analyze the predictive effect of MCI on the scores of QOL facets controlling for well-established variables like age and marital status.

In our sample, 12.2% of participants were diagnosed with MCI. This relatively low percentage, compared to other current studies [10], is a consequence of the application of strict criteria for MCI diagnosis [32]. Our univariate comparison of participants with and without MCI showed significant differences for QOL for the facets autonomy; past, present, and future activities; social participation; death and dying; and intimacy. With the exception of death and dying, the non-MCI group constantly showed higher levels of QOL. This could point to the fact that in case of MCI, existential fears are to some extent replaced by more proximate fears and worries related to daily living. The regression analysis, including multiple control variables, confirmed MCI diagnosis as a significant predictor of impaired QOL in the facet autonomy.

Our results from the univariate analysis show that MCI has a tendency to affect QOL in a negative way. This matches with other studies where MCI had a negative association with psychological QOL [20] and with QOL measured via subject and informant ratings [29]. The fact that there was no difference between MCI and non-MCI groups in terms of QOL with regard to sensory abilities is most likely a consequence of the strong impact of seeing and hearing abilities on this specific facet. In the multivariate analysis, we can find an impact of MCI-status on the facet autonomy. This makes sense, since the decline of cognitive abilities, and the fear of further deterioration, directly affects individuals’ ability to live independently and take own decisions. In addition, some researchers emphasize the importance of promoting autonomy in order to increase health-related QOL of people with MCI [3]. Since MCI is far less severe than dementia and more heterogenic in outcome [32], impairments are smaller and less visible to others. Therefore, MCI may not so much affect social interactions as reflected in the facets intimacy and social participation. The fact that MCI was not associated with social participation can be seen as a potential resource for those affected by MCI, since frequency of engagement in social activities is linked to a lower risk of progression from mild to severe forms of cognitive impairment [11] and social activities are connected to reduced dementia risk [12].

Results indicate that, especially, autonomy is associated with MCI. In the light of high prevalence of MCI among older people, these results have implications for the management of MCI. For example, participants may benefit from interventions to boost autonomy and/or cope with decreasing independence.

From a methodological point of view, our results show that in order to understand the burden of MCI on the older population, a differentiated approach, using specific facets rather than a total score, is highly recommendable.

From the perspective of research, interactions between facets are of great interest as well as the causal mechanisms and the neuronal, behavioral and psychological processes that link MCI to QOL. Furthermore, future research may differentiate between the effects of amnestic vs. non-amnestic MCI and take into account the severity of impairment.

Reduced QOL, especially over longer periods of time, may have multiple consequences for individuals on a psychological, physiological, behavioral, and social level. Clearly, more research is needed in this area.

While this study has several advantages, e.g., the comprehensive assessment of MCI and QOL, and a well-described cohort of individuals in late life, our research also has certain limitations. For living situation and the ability to walk, see and hear, answering options were merged for analysis due to the small amount of participants attached to specific options. Further research would benefit from a more differentiated approach to MCI with regard to type, amnestic vs. non-amnestic, and degree of severity. In addition, our analysis is cross sectional which limits our ability to make a causal claim to the findings of the study.