Andrea TownsendAs Associate Professor of Biology Andrea Townsend was investigating how infectious disease affects the problem-solving performance of American crows, she was surprised to discover how few studies compared the effects of disease on cognition in other species.

Further intrigued by the fact that many people Townsend knew who had contracted COVID also reported experiencing brain fog, she decided to bring existing studies together for comparison and examination.

Working with several fellow researchers, Townsend recently published “Infectious disease and cognition in wild populations” in Trends in Ecology & Evolution. The article explains how learning, memory, and problem-solving are impaired by infection, not just in humans, but in species throughout the animal kingdom. The reasons vary — from damage by a parasite, immune response to infection, lack of motivation of sick individuals to perform a cognitive task, malnutrition, or even alterations to the host microbiome.

“I think one surprising thing for me was how little is known. We’re seeing an accelerated emergence of all of these infectious diseases, and yet we know very little about how disease might affect cognition and the implications of this for wild animals as well as for humans,” she says.

“We’re seeing an accelerated emergence of all of these infectious diseases, and yet we know very little about how disease might affect cognition and the implications of this for wild animals as well as for humans.”

Cognitive impairment linked to disease has the potential to affect entire ecological communities. For example, bees infected with some pathogens have difficulty learning the smells and colors of the most productive flowers. “This is really a bad outcome, if you are a bee, because foraging success depends on the ability to efficiently find the most productive flowers,” Townsend adds. This could have negative consequences for bee populations, and also for the flowers, which rely on bees for pollination.

crows flyingAs wild animals continue to be affected by a changing climate and disturbed environments, cognitive impairment may exacerbate the effects of disease. In disturbed environments, animals tend to be stressed, and stressed animals are more likely to get sick, which could impair their cognitive abilities. At the same time, these cognitive abilities could be especially important in these changing, stressful environments, where cognitive abilities — such as flexible decision-making and innovation — could give them a behavioral buffer.

“So, here you might have a snowball effect where animals in stressed environments are more likely to get sick and their cognitive abilities are impaired. Then they are less able to deal with these stressful, changing environments because of their impaired cognitive abilities. It could increase the costs of environmental change for some wild animals,” Townsend explains.

Excerpted from an article on EurekAlert!, news from the American Association for the Advancement of Science.

Published in Fall 2023 Hamilton Magazine

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