Cognitive impairment and happiness in old people in low and middle income countries: results from the 10/66 study.

BACKGROUND

Recent studies indicate that happiness increases with age, except in those with dementia-related diseases. We investigated the relationship between cognitive decline and happiness, hypothesising that this relationship is modified by social networks and depression.

METHOD: The 10/66 study involved cross-sectional representative surveys of residents aged 65+ in India, China and Latin America. 14,769 (98.7%) participants answered the single item happiness measure. We used the Community Screening Instrument for Dementia, and the Geriatric Mental State to identify depression.

RESULTS

12,150 (82.3%) participants reported they were very or fairly happy. Better cognition was associated with greater happiness, after controlling for sociodemographic characteristics and physical disability (t=3.3, p=0.001). This association was no longer significant after controlling for social network type as a main effect (t=1.9, p=0.06) and as an interaction term with cognition (t=0.07, p=0.94). People with more cognitive impairment were happier if they had "family dependent" rather than "private" social networks characterised by minimal social contact (β=-1.0, p<0.001).

LIMITATIONS: This is a cross-sectional survey, so we cannot show direction of causality.

CONCLUSION

Most of the older people reported that they were very or fairly happy, and happiness increased with age. Cognitive impairment was not associated with unhappiness after controlling for the modifying effect of social network type. Unhappiness is therefore not inevitable in those with cognitive loss, and supporting social networks are important in maintaining happiness. Trials of interventions to strengthen social support in those with cognitive impairment are indicated to determine whether this approach promotes happiness.