Cheryl Faye Harding

I have recently switched my research area from behavioral neuroendocrinology in birds to behavioral neuroimmunology in mice.  Over the last few years, evidence has mounted that exposure to mold causes a broad range of health problems.  While the aftermath of Hurricane Katrina presented vivid images of building interiors covered with mats of black mold, Americans who live in other areas are also at risk, because of faulty building designs and inadequate maintenance.  According to some estimates, 40% of American buildings are moldy. 

While there are still those who claim that exposure to mold poses no health risks, there is solid documentation of adverse effects on most body systems following mold exposure.  As a neuroscientist, I am particularly intrigued by the effects of mold exposure on neural function and cognition.  Recent research has documented that people who lived or worked in moldy buildings had multiple cognitive problems.  In one study, 80% of mold-exposed individuals reported CNS-related symptoms, including headaches, difficulty concentrating, fatigue, dizziness, and anxiety.  While mold exposure does not appear to affect IQ, it does affect learning and memory.  Compared to controls, mold-exposed individuals in one study scored below the 10th percentile on a number of cognitive tests.  The most consistent deficits were in visuospatial learning, visuospatial memory, verbal learning, and psychomotor speed.  In other studies, measurements of brain activity in mold-exposed patients demonstrated neurological deficits that correlated with their cognitive problems. Perhaps one of the most striking findings was that multiple studies concluded that individuals exposed to mold suffered cognitive deficits that could not be distinguished from those of patients suffering from traumatic brain injury. In addition, about 20% of Americans appear to be genetically-susceptible to long-term inflammation with resulting medical problems following mold exposure.

My current research seeks to develop a mouse model of the effects of mold exposure on neural and cognitive function.  No such animal research has been published to date.  My basic hypothesis is that exposure to mold activates an innate immune response in the brain just as it does in peripheral tissues like the lungs. Prolonged innate immune activation is known to cause adverse neurological consequences.  First, mice are given basic physiological and cognitive tests.  They are then exposed to control or mold stimuli and retested.  We compare individuals’ performances pre- and post-exposure and as well as looking for differences in performance between groups following mold or control exposures.  We then use immunohistochemical techniques to look for differences in brain structure and chemistry between groups following mold exposure.  We measure the number, size, and morphology of microglia, the primary immune cells found in the brain.  We quantify the production of several cytokines released by immune cells and neurons.  These chemicals are known to cause inflammation.  Finally, we quantify neuron birth and death in the hippocampus, since these processes can have a major impact on learning and memory in our cognitive tasks.  Finally, the animals’ performance on the cognitive tests following mold exposure is compared to their measures of neural function to determine possible relationships. We have just begun this NIH-funded research and do not yet have any publications in this area.