Microbes on Your Mind.docVIP

Scientific American Mind?(July/August 2012),?23, 32-37?Published online: 7 June 2012 |?doi:10.1038/scientificamericanmind0712-32 Microbes on Your Mind Moheb Costandi Abstract Bacteria in your gut may be influencing your thoughts and moods Introduction topof page FAST FACTS Moody Microorganisms Bacteria and viruses dwelling in our gut produce compounds that can interact with our nervous system in ways that appear to affect our anxiety and stress responses. Early clinical trials suggest that bacterial remedies, such as probiotic supplements, may be useful in treating several types of psychological distress. Eventually individual assessments of gut microbial communities could allow physicians and researchers to tailor treatments for mental disorders. The thought of parasites preying on your body or brain very likely sends shivers down your spine. Perhaps you imagine insectoid creatures bursting from stomachs or a malevolent force controlling your actions. These visions are not just the night terrors of science-fiction writers—the natural world is replete with such examples. Take?Toxoplasma gondii, the single-celled parasite. When mice are infected by it, they suffer the grave misfortune of becoming attracted to cats. Once a cat inevitably consumes the doomed creature, the parasite can complete its life cycle inside its new host. Or consider?Cordyceps, the parasitic fungus that can grow into the brain of an insect. The fungus can force an ant to climb a plant before consuming its brain entirely. After the insect dies, a mushroom sprouts from its head, allowing the fungus to disperse its spores as widely as possible. Microbes that manipulate the behavior of their host are not limited to natures dark corners, although those examples are vivid. Our body hosts vast numbers of foreign microorganisms, some of which wield unseen powers over us. These microbes are not parasites—they live on and in our body, mostly in our gut, and often strike up a symbiotic relationship with u