The Link Between Lyme Disease and Dementia
Lyme disease results from infection with the bacterium Borrelia burgdorferi, which is transmitted to humans through the bite of some ticks. Common early symptoms of the illness include fever, headache, fatigue and a characteristic red rash (erythema migrans) at the site of the tick bite.
Early diagnosis is crucial. The sooner Lyme disease is recognised, the easier it is to cure fully with a course of oral antibiotics. As the infection progresses, it may become a lot more persistent. If left untreated for a long time, Lyme disease may enter a chronic phase. The infection can spread throughout the body and cause serious joint, heart and neurological symptoms.
Since the erythema migrans rash is absent in 20–30% of patients and the other symptoms can mimic other illnesses, Lyme disease is often difficult to diagnose. The available laboratory tests are also unreliable in the early stages of the illness. Therefore, doctors have to consider factors such as the patient’s history of tick bites and recent visits to high-risk areas, in addition to any physical signs and symptoms, when making a diagnosis.
Lyme Disease and the Brain
Some common questions about Lyme disease and the brain are ‘Can Lyme disease cause dementia-like symptoms?’ and ‘Does Lyme disease cause memory problems?’ To answer these, let’s take a look at the stats.
Lyme disease leads to profound effects on the brain in about 15% of cases. Some sources suggest that this proportion may be even higher, since thousands of cases are believed to remain undiagnosed every year. A small percentage of patients continue to experience neurological symptoms after receiving timely antibiotic treatment for Lyme disease. This phenomenon is often referred to as ‘post-treatment Lyme disease syndrome’, and its possible cause is a widespread inflammation of the brain.
Neurological Symptoms of Lyme Disease
Chronic Lyme disease develops when the infection remains unrecognised and untreated for a long time. In patients with strong immune systems, the initial symptoms can be very mild and may even go unnoticed. The bacteria can live inside the cells and not cause any problems for several months or even years.
Serious symptoms of chronic Lyme disease tend to first appear when immune function becomes disrupted due to another illness, stress or environmental factors. This is when the bacteria begin to proliferate at a greater pace, and travel to various different tissues and organs.
When Lyme disease becomes chronic and the bacteria spread to the brain, the resulting condition is referred to as neuroborreliosis. Common neurological and psychological symptoms of neuroborreliosis are cognitive decline, memory impairment, mood swings, decreased energy levels, difficulty concentrating, sleep disturbances, disrupted fine motor control and vision changes.
In rare cases, neuropsychiatric Lyme disease can cause paranoia, hallucinations, mania and obsessive-compulsive symptoms. In children, the most common symptoms of neuroborreliosis are headaches, behavioral changes, learning difficulties and sleep disorders.
Patients with chronic Lyme disease often report extreme fatigue. They can sleep for as many as 10 to 12 hours, yet not feel rested after waking up. Increased sensitivity to light and loud sounds can also develop.
Diagnosing Neurological Lyme Disease
In addition to serological testing, patients with suspected neuroborreliosis may benefit from a brain MRI scan. The scan may reveal lesions similar to those caused by multiple sclerosis. Spine lesions have also been observed in some cases. Other diagnostic methods to consider are nerve conduction studies and neurocognitive tests.
Secondary Dementia Due to Lyme Neuroborreliosis
Severe dementia resulting from neuroborreliosis is extremely rare. However, dementia-like syndromes associated with Lyme disease have been reported on occasion.
In a few cases, the condition has seemed to trigger primary dementia, such as Alzheimer’s disease. Persistent chronic Lyme disease is normally treated with several courses of intravenous antibiotics, but it’s unclear whether serious neuropsychiatric symptoms are completely reversible.
Lyme Disease and Dementia/Alzheimer’s Disease
The dementia and other signs of cognitive decline caused by severe neuroborreliosis tend to resemble the symptoms of Alzheimer’s disease. Some research studies have indicated the presence of Borrelia burgdorferi in the brains of Alzheimer’s patients, suggesting a possible link between the two conditions. While Lyme disease can be successfully cured with antibiotics in most cases, the exact causes of Alzheimer’s disease remain unknown, and no effective treatment currently exists.
So how does Lyme affect you in old age? Well, one 2014 study aimed to determine if there was an actual relationship between Lyme and Alzheimer’s. The scientists collected data from the US Centers for Disease Control and Prevention on the incidence of Lyme disease and deaths associated with Alzheimer’s disease. They then analysed the information in search of any significant correlations.
One of the findings of the study was that the 13 states with the highest prevalence of Lyme disease actually had the lowest number of deaths from Alzheimer’s disease. Moreover, the seven states with the highest incidence rates of Alzheimer’s were among the 13 states with the fewest number of Lyme disease cases. Vermont was the only state reporting a high incidence of both conditions. Any other potential associations were found to be statistically insignificant.
The link between Lyme disease and dementia remains unclear, but considering the other possible implications of contracting chronic Lyme, it’s better to be safe than sorry and protect yourself against tick bites altogether.