Could a bout of the sniffles make you stupid? According to a new study published in the journal , infections or related immune responses could have a negative effect on a person’s IQ. But don’t worry about your Mensa membership at the first sign of sinusitis; it’s the more serious infections that have the capacity to lower IQ. Researchers from Aarhus University in Denmark found that people who endured infections that required hospital stays scored 1.76 units lower on a cognitive ability test, compared to those who didn’t see the inside of a patient room. What’s more: As the number of hospital stays for infections rose, a patient’s IQ dropped—those who had 10 or more hospital admissions for infections scored 5.54 units lower than their healthy counterparts. Researchers believe the decrease in brainpower is due to our immune response to infection—inflammation (which is essentially an immune response) changes the way cells communicate with the brain. These 10 foods can help soothe inflammation.)Cancer The C-word itself may not directly impact your intellect, but a common treatment for it might. Hence the term “chemo brain.” A study published in the Journal of Clinical Oncology reports that cyclophosphamide, methotrexate, and fluorouracil (CMF) chemotherapy—a treatment for early-stage breast cancer—may cause decreased cognitive performance (If you’re one in eight women diagnosed, this guide is here to help). Researchers found that women exposed to chemotherapy performed significantly worse on cognitive tests, including memory and processing speed, than those who had never undergone chemotherapy—and the results were long-lasting, enduring for 20 years or longer. While the cause behind chemotherapy’s effect on cognitive performance is still unclear, the study suggests that structural differences in brain matter exposed to chemotherapy may be to blame.ConcussionsRadiology A bump on the head could have a negative impact on your working memory—especially if you’re a woman, suggests new research from the journal . According to reseachers from Taipei Medical University in Taiwan, women with a mild traumatic brain injury (like a concussion) had a lower score when their working memory was tested via magnetic resonance imaging (MRI) than those who hadn’t had a brain injury—or even men who had sustained a brain injury. Researchers hypothesize that women are more vulnerable to brain injury than men, and may ultimately take longer to heal. MORE: 5 Weird Things Fast Food Does To Your BrainInsomnia Racking up the sleepless nights may do more than just make you perpetually tired and cranky, suggests researchers from the University of Pennsylvania’s Perelman School of Medicine. The study, which used mice to track the effects of chronic sleep loss, was published in The Journal of Neuroscience and suggests that extended periods of wakefulness leads to irreversible physical damage to and loss of brain cells—especially those that are essential for alertness and optimal cognition—in rodents, and quite possibly in humans. Researchers believe a reduction in sirtuin type 3 (SirT3) protein, which acts as protection for neurons, is to blame. Without proper sleep, those neurons don’t get the chance to recover from wakefulness, which then hinders their performance. (Sleep better, balance your hormones, and finally lose weight with the The Hormone Reset Diet!)Lyme Disease Protecting your IQ may be one more reason to douse yourself in bug spray and tuck your pants into your socks before going out for a hike. Along with extreme fatigue and muscle and joint pain, hindered brain functioning can also be a symptom of Lyme disease, according to Leo Shea, PhD, president of the International Lyme and Associated Diseases Society. “There can be a decline in the processes of brain function—attention and concentration problems, memory problems, and the inability to deal with multitasking,” says Shea. The cause? Increased pressure in the head—the same cause of the intense headaches many suffering from Lyme disease report—restricts blood flow to the brain, depriving it of the oxygen it needs to function properly.