Social isolation worsens effects of Alzheimer's disease, study finds

Social isolation worsens the effects of Alzheimer's disease, increasing anxiety and asymmetry in brain atrophy, according to a new study by the Universitat Autònoma de Barcelona in Spain and published in the journal Frontiers in Psychiatry.

The study, conducted in mice, found hyperactivity levels reaching up to twice as much as in the pathology itself, as well as an increase in the asymmetric atrophy of the hippocampus, a brain area central to memory.

The researchers analyzed the effects of isolation in male mice models suffering from advanced stages of Alzheimer's disease through a series of behavioral tests, which could be compared to several areas found in elderly residence homes. They compared these results with mice models of Alzheimer's that were not isolated, and with other healthy animal models undergoing a normal ageing process, according to the study.  

The study was conducted with male mice because these are more affected by novel coronavirus (COVID-19) and are also the ones to show more deterioration of the neuro-immuno-endocrine system and worse survival conditions when suffering dementia, the authors said.

The main findings demonstrate that isolation exacerbates hyperactivity up to twice as normal in mice with Alzheimer's disease, and causes the appearance of strange behaviors. This increase was demonstrated consistently in the gross motor skills, related to the movement of arms, legs, feet or the entire body. However, it also affected fine motor skills, small movements made by hands, wrists, fingers, toes, lips, and tongue, the researchers said. The isolated animals showed emotional patterns comparable to anxiety and changes in their stress management strategies, they said.

Researchers also analyzed the effects of isolation on other neuropathological variables. They found that, although the characteristic variables of the disorder, like tauopathy, were not modified, some others such as asymmetric hippocampal atrophy increased with isolation. 

The study also confirmed that the mice suffering from Alzheimer's disease lost body and renal mass, effects which also have been observed in COVID-19 patients, although the loss was greater with those in isolation. The loss in spleen mass, an important organ of the peripheral immune system, was only observed in isolated animals.

The researchers said the study highlights the need for personalized interventions adapted to the heterogeneous and complex clinical profile of people with dementia, and to consider how all of this affects the obligations of caregivers, whether they be professionals or members of the patient's family.

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