The medical community has long believed there is a stroke/head injury connection to Alzheimer's Disease (AD). However, scientists didn't know exactly "why" that was the case. Without a surefire cause, it was impossible to create a workable treatment for AD. But recent studies have shed more light on this dark disease, pinpointing the biology behind the stroke/AD connection.
Prevalence
The chance of developing AD and related dementias doubles after a stroke, according to information provided by the Alzheimer's Society of the UK. Research also finds that one may remain more susceptible to AD many years after the stroke has occurred. It is believed that during the stroke, the oxygen to the brain is depleted, and, over time, toxic chemicals related to the onset of AD build up. In addition, the size or severity of the stroke doesn't seem to matter; barely noticeable, almost asymptomatic strokes are often believed to be the culprits behind the development of AD in some patients.
Amyloid Plaques
From the time Dr. Alois Alzheimer first noted and described amyloid plaques in 1906, these abnormal structures are considered the primary culprits behind AD, and have long been thought to be responsible for the destruction of neurons. It is believed that head trauma or stroke prompts an increased presence of these structures, but exactly how is unknown.
BACE
Researchers have discovered that after a stroke, the body is less able to destroy the BACE enzyme, which is responsible for creating the dangerous plaques. BACE actually works by effectively separating proteins called amyloid precursors, resulting in an abbreviated protein called A beta peptide. Those peptides then foster the plaques so central to precipitating the impacts of AD by killing brain cells.
Biochemical Events
With regard to the onset of AD, studies show that any insult to the brain or change in blood flow can have future ramifications. It is believed that strokes interrupt the body's natural biochemical cycle, reducing its ability to defend against toxic peptides and plaques.
Oxygen Depletion
When exploring AD in those who have experienced strokes, researchers at the University of Leeds have focused on lack of oxygen as a cause. They found that when the brain doesn't get the oxygen it needs, though the patient may outwardly appear to be healthy, irreparable cell damage may have occurred; brain cells, starved of oxygen, are not able to absorb key chemicals, allowing these chemicals and amyloid proteins to accumulate to toxic levels. Researchers have taken these theories one step further --- studying anyone who might be in an oxygen-starved state, including those with sleep apnea.
Treatment
There remains no cure for AD, since the roots of the disease are still not understood. Researchers are looking to develop new drugs to treat the biochemical imbalances caused by a stroke and believed later to be responsible for the onset of AD.
Tags: after stroke, believed that, brain cells, culprits behind, Researchers have