By now, we know that COVID isn't just a simple respiratory disease—it affects a wide range of body systems. In particular, doctors are learning more and more about its potentially devastating effect on the brain: In one new study conducted at Northwestern University, one-third of hospitalized COVID patients showed signs of altered mental function, including confusion and delirium. Those patients stayed in the hospital three times longer, and only 32 percent of them were able to resume normal daily activities after being discharged. Experts think this may be triggered by the virus's tendency to cause inflammation and impair blood circulation. These are some of the scary neurological symptoms associated with COVID. Read on, and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had Coronavirus. 1 Brain Fog Many COVID patients report that they feel confused at times, or unable to concentrate or focus. This "brain fog" can last for weeks or months. In August, a study published in the Lancet found than 55% of people diagnosed with coronavirus have neurological symptoms three months after their diagnosis. 2 Dizziness COVID frequently causes dizziness, vertigo and fainting. Some COVID patients report that they feel dizzy when they stand up after sitting or lying down. This is called orthostatic tachycardia, which is caused by a sharp rise in heart rate when you stand. It's very common: Thirty percent of patients in the Northwestern study reported dizziness.RELATED: CDC Warns of Deadly New COVID Syndrome 3 Stroke In a particularly scary development, doctors have been mystified by the fact that previously healthy young people with no risk factors have suffered COVID-related strokes, some fatal. This seems to be related to the coroanvirus's tendency to cause blood clots in the brain (leading to stroke), heart (causing heart attack) and lungs (which creates pulmonary embolisms). 4 Dysautonomia While they're recovering, some COVID patients have reported this obscure condition, in which the communication system between the brain and nerves goes haywire. Symptoms include problems with breathing and digestion, insomnia, migraines, numbness in the hands and feet, racing heart rate and anxiety-inducing periods of shortness of breath. Scientists don't know what causes it. 5 Memory Loss "My memory is really bad," one 28-year-old COVID patient recently told Medium, likening her symptoms to a bad concussion. "For a while, I couldn't think of really basic words or definitions. I went weeks without talking to anybody because it was too much work." This may be caused by the virus damaging blood vessels in the brain. RELATED: 11 Symptoms of COVID You Never Want to Get 6 Mental Health Issues Coping with a largely unknown, potentially deadly illness like COVID-19 can take a serious toll on mental health, causing anxiety, depression, even post-traumatic stress disorder (PTSD)—all of which may need treatment long after the physical symptoms of COVID have resolved. 7 Confusion The CDC recently added "new confusion or inability to arouse" to their list of serious coronavirus symptoms that require emergency medical attention. This can indicate that coronavirus has caused inflammation in the brain. 8 Delirium In August, NBC News reported that doctors were seeing a surprising symptom in young COVID-19 patients: delirium, which is characterized by confusion and a reduced awareness of the environment. Forty percent of hospitalized patients may experience it.RELATED: 11 COVID Symptoms No One Talks About But Should 9 Loss of Smell and Taste In a study published in the Journal of the American Medical Association, sixty-four percent of people with coronavirus reported a loss of smell or taste. A recent CDC survey found this tends to last, on average, eight days. But some people experience it for weeks. Like so many facets of COVID-19, health experts aren't sure why this happens. 10 How to Stay Healthy As for yourself, do everything you can to prevent getting—and spreading—COVID-19 in the first place: Mask, get tested if you think you have coronavirus, avoid crowds (and bars, and house parties), practice social distancing, only run essential errands, wash your hands regularly, disinfect frequently touched surfaces, and to get through this pandemic at your healthiest, don't miss these 35 Places You're Most Likely to Catch COVID.