[Social isolation during old age worsens cognitive, behavioral and immune impairment]

Several studies by the World Health Organization indicate that widows and widowers show lower physical and mental health indexes than the age-matched general population. In addition, widowhood and social isolation are common in the elderly, with women being more affected than men due to their longer life span. Thus, the aim of the present study was to create an animal model of solitude in old age to study the behavioral, cognitive and immunological changes induced by social isolation at this late stage of life.

Twenty female C57b/129sv mice, housed in groups of 4-5 until their old age (18 months), remained in groups (controls, n=10) or were isolated after reaching the age of 18 months and until they reached the age of 24 months (isolated, n=10). At this advanced age, the animals were submitted to a battery of tests to assess neophobia (corner test), anxiety (open-field test), and learning and memory (Morris water maze). Thereafter, the animals were sacrificed and the thymus was removed. The natural killer (NK) activity of the thymic cells against the YAC-1 murine tumor cell line was evaluated.

Animals isolated during old age showed functional and cognitive decline, with increased neophobia and anxiety as well as learning and memory deficits. In addition, isolation reduced the NK activity of thymic cells.

We demonstrate the importance of social isolation and solitude during old age. Both social isolation and solitude exacerbate mental and immunological involution during this period, despite normal social life during previous stages of life.