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Brain Fog

Hepatitis C virus can cloud cognition

By Sarah Aldridge | 04.25.2011
Originally Published April 2011
Brain fog

For years, patients with hepatitis C have complained of loss of concentration, memory lapses and shortened attention span. It turns out that these symptoms are not just in their mind. The hepatitis C virus (HCV) can cause hepatic encephalopathy, or altered brain function, commonly called “brain fog.”

“Some of the symptoms can be quite subtle, ranging from sleep disturbance to increased irritability,” says Kenneth Sherman, MD, PhD, Gould Professor of Medicine and director of the Division of Digestive Diseases at the University of Cincinnati Academic Health Center. “In more severe stages, there can be changes in mood, personality and ability to accomplish jobs that require both short-term and long-term memory.” Motor skills can also be affected, he says. Several studies indicate that some patients with hepatic encephalopathy have higher rates of car accidents and violations.

It is believed that HCV affects the brain in two ways: directly, by penetrating the blood-brain barrier and affecting neurons, and indirectly, via the buildup of toxic substances in the liver. In the direct method, the presence of the virus activates the immune response in the brain, producing cytokines, which cause inflammation. Cytokines are toxic to neurons, causing changes in brain function.

In the indirect method, HCV damages the liver, preventing it from detoxifying nitrogen-containing neuroactive substances, such as ammonia. Those substances can be carried in the blood to the brain, where they disrupt cognitive function. Adding a diagnosis of HIV can add to the brain fog. “HIV seems to be associated with neurocognitive impairment as well,” Sherman says. HIV secretes several proteins that are toxic to neurons. Further, some HIV drugs affect the brain.

Cognitive Testing

To assess the level of mental impairment, patients can undergo a battery of cognitive assessment tests. For example, the number connection test measures how long it takes to connect a random series of numbers on a page using a continuous line. “The time it takes to do that begins to increase in a patient with HCV so that it becomes an objective measure of that neurocognitive dysfunction,” Sherman says.

In a study published in 2002 in Hepatology, Daniel M. Forton, PhD, and colleagues showed that patients with HCV who were tested using a computer-based system fared worse on concentration and memory recall than patients who had cleared the virus.

Although treatment for hepatitis C is not ideal—most people have troubling side effects and only half clear the virus—patients are encouraged to try it. Clinicians have measured patients’ quality of life after they achieved sustained viral response, or clearance of HCV, through questionnaires that have separate scores for physical and mental health. “Both seem to improve, suggesting that there is an overall improvement in patients’ perception of the quality of their life in the mental arena,” Sherman says. But the perceived mental improvement has not yet been confirmed through advanced neurocognitive testing, he says.

If you have hemophilia and HCV and feel you’re in a fog, it might be time to meet with your liver specialist to discuss your symptoms. Some cognitive testing might be in order.