And for all ages, the worse the sepsis, the greater the risk of developing dementia. Another study published in 2010 estimates that there may be as many as 20,000 new cases of dementia every year caused by sepsis.
Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Sepsis causes cerebral dysfunction in the short and long term and induces disruption of the blood–brain barrier (BBB), neuroinflammation, hypoperfusion, and accumulation of amyloid β (Aβ) and tau protein in the brain.
Sepsis is a potentially life-threatening condition caused by a systemic dysregulated host response to infection. The brain is particularly susceptible to the effects of sepsis with clinical manifestations ranging from mild confusion to a deep comatose state.
Some of the infections that are thought to be linked to Alzheimer's include oral herpes, pneumonia and infection with spirochete bacteria (the type which cause Lyme disease and some types of gum disease).
Survivors from sepsis have presented with long-term cognitive impairment, including alterations in memory, attention, concentration, and global loss of cognitive function.
They concluded that septic patients have a high mortality rate after two years of hospital discharge compared to patients recovered from other diseases; the percentage of death ranged from 22% to 70%.
The affected areas included the frontal lobes, thalamus, and cerebellum. Another MRI study presented evidence of prominent atrophy of the left hippocampus in sepsis survivors who had permanent cognitive deficits in verbal learning and memory 6 to 24 months after discharge from the ICU (112).
Some possible causes include: Autoimmune diseases (conditions that over-activate the immune system) Unusual presentations of more common neurodegenerative diseases (such as Alzheimer's disease) Prion diseases (rare forms of neurodegenerative disease)
Most cases of sudden confusion and rapidly progressive dementia in an elderly person are due to delirium caused by infection.
These changes are present in the most severe cases. The parts of the brain mostly involved in sepsis are the frontal cortex and the hippocampus, which leads to cognitive dysfunction [23]. There might be a brainstem dysfunction caused by the passage of inflammatory mediators through area postrema.
Many people who survive sepsis recover completely and their lives return to normal. However, as with some other illnesses requiring intensive medical care, some patients have long-term effects.
The duration of delirium in intensive care patients is associated with long-term functional disability and cognitive impairment, although this syndrome usually reverses after the successful treatment of sepsis.
Encephalopathy is associated with altered electroencephalographic activity, but less frequently with neuroimaging changes1,2. A complete recovery is possible, while on the other hand, brain death is almost never observed as a direct consequence of sepsis.
It is also important to be aware that any infection could speed up the progression of dementia and so all infections should be identified and treated quickly.
Memory problems
Difficulties with memory are the most well-known first signs of dementia. For example, a person may not recall recent events or may keep losing items (such as keys and glasses) around the house. Memory loss is often the first and main symptom in early Alzheimer's disease.
For an individual with dementia, the onset of medical problems such as pneumonia, a urinary tract infection or poorly controlled diabetes can rapidly lead to worsening confusion and agitation. As a general rule, dementia does not progress overnight.
Rapidly progressive dementias (RPDs) are neurological conditions that develop subacutely over weeks to months, or rarely acutely over days. In contrast to most dementing conditions that take years to progress to death, RPD can be quickly fatal.
Sepsis-associated delirium (SAD) is a cerebral manifestation commonly occurring in patients with sepsis and is thought to occur due to a combination of neuroinflammation and disturbances in cerebral perfusion, the blood brain barrier (BBB) and neurotransmission.
Many patients who survive severe sepsis recover completely, and their lives return to normal. But some people can have permanent organ damage. For example, in someone who already has impaired kidneys, sepsis can lead to kidney failure that requires lifelong dialysis.
When the infection-fighting processes turn on the body, they cause organs to function poorly and abnormally. Sepsis may progress to septic shock. This is a dramatic drop in blood pressure that can lead to severe organ problems and death.