Global cognition modifies the relationship between anemia and depression in old age: A longitudinal analysis of the...

To examine the relationship between anemia and depression and whether sex and global cognition modify this relationship over a 4-year follow-up.

Longitudinal analysis of an international cohort study SETTINGS AND PARTICIPANTS: Older adults from the International Mobility in Aging Study (IMIAS) aged between 65 and 74 years at baseline.

Participants were recruited in Natal (Brazil), Manizales (Colombia), Kingston (Ontario, Canada), and Saint-Hyacinthe (Quebec, Canada). The study outcome was depression, defined by a score of ≥16 in the Center for Epidemiologic Studies Depression Scale. Longitudinal associations over a 4-year follow-up were examined using generalized estimating equations. Cognition was ascertained with the Leganes Cognitive Test with scores ≤ 22 indicating poor cognition. Models were also adjusted for research sites, marital status, alcohol drinking status, body mass index, chronic conditions, activities of daily life disabilities, and polypharmacy.

Anemia and poor cognition at baseline were associated with an increased risk of depression at follow-up (OR = 5.73, 95% CI: 1.58-20.78). Global cognition was also an effect modifier of the longitudinal association between the severity of anemia and depression.

In international samples of older adults, anemia, as well as the severity of anemia, were independent risk factors for depression, and the effect of these associations was modified by global cognition. The findings highlight an important issue as to whether depression in old age may be at least partially preventable through public health interventions to correct low Hb levels.