Effects of restriction of activities and social isolation on risk of dementia in the community.

OBJECTIVE: Social isolation and emotional isolation, i.e. loneliness, have been associated with dementia or cognitive decline. In contrast, the relationship of restriction of physical and instrumental activities of daily living to cognitive decline and dementia has been less studied. DESIGN: We examined multiple quality of life (QoL) indicators, including isolation and restriction of activities, utilizing two validated scales in elders without dementia to determine their associations with cognitive decline and incident dementia that were followed longitudinally over 6 years. We comprehensively controlled for other symptom constellations, including depression and anergia. SETTING: A large multi-ethnic prospective study was conducted in northern Manhattan, NYC. PARTICIPANTS: An ethnically diverse sample of 855 non-demented individuals at baseline participated. MEASURES: The following QoL scales were utilized: Restriction, Anergia, Isolation, Loneliness, and Affective Suffering. RESULTS: Both Restriction (HR = 2.22, 95% CI [1.42, 3.47], P < .001) and Isolation (HR = 1.78, 95% CI [1.17, 2.70], P = 0.007) were associated with episodic memory and incident dementia, controlling for age, sex, and education. Loneliness and Affective Suffering (depression) were not associated with these outcomes (P's > .1) with both Restriction and Isolation in the same model for the prediction of dementia, only Restriction remained significant (HR = 1.97, 95% CI [1.24, 3.14], P = 0.004). In cross-lagged panel analyses, Restriction and Isolation had reciprocal influences (P's < .001), indicating that Restriction at the previous time point influenced current Isolation. Importantly, Restriction (but not Isolation) and Selective Reminding total recall memory demonstrated highly significant direct and reciprocal influences over time (P's < .001). CONCLUSIONS: Restriction and Isolation were associated with incident dementia. Restriction played a more prominent role in its impact on memory decline. The development of these impairments in QoL, particularly Restriction, may provide warning signs of future cognitive decline and dementia and provide multiple and novel avenues for therapeutic interventions with the goal of delaying the development of cognitive decline and dementia.