Historically, heart disease has been the biggest killer of individuals in the UK. However, dementia – a disorder which is characterised by memory loss and difficulties with thinking, problem-solving, navigation and/or language – has, for the first time ever, overtaken heart disease as the leading cause of death in individuals in England and Wales. There are currently more than 850,000 people in the UK living with dementia, with the increase in dementia related deaths thought to be a result of the exponential increase in the disease’s prevalence, linked to the ageing population by the Office for National Statistics. In a hope to stop this trend, researchers are focusing both on more effective treatments, and early diagnosis.

The most common cause of dementia is the neurodegenerative disorder Alzheimer’s, which usually occurs in the elderly. It results in a progressive brain disease, leading to a loss of connections between neurones, a decrease in vital neurotransmitters, neurone death and a loss of brain tissue. The exact cause of Alzheimer’s is unknown, but there are many predictions on why the brain begins to break down.

One of the most common theories of Alzheimer’s, and therefore dementia development, suggests that neurodegeneration is caused by a biological process known as the amyloid cascade. Amyloids are proteins which can aggregate and be deposited around the body. According to the amyloid cascade theory, a protein called amyloid precursor protein – which normally promotes cell growth, survival and motility and is found predominately at neurone synapses – is broken down into β-amyloid proteins. Soluble β-amyloid proteins are then deposited around neurone synapses, aggregating into plaques which are thought to be toxic, killing the cells, and leading to dementia.

Another theory focuses on the levels of neurotransmitters in the brain. Acetylcholine (ACh) is a key neurotransmitter which plays an important role in learning and memory. It has been suggested that a loss of ACh results in defective learning and memory areas of the brain, again causing visible dementia symptoms.

Whilst the definitive cause is not known, it is assumed that the disease results from various different issues, including the theories outlined above. Unfortunately, the current treatments available for dementia and Alzheimer’s are not that effective. Scientists have tried to increase the level of ACh in the brain using donepezil; a drug which prevents the breakdown of ACh, thus increasing its concentration in the central nervous system. Whilst this drug has variable effects in patients, it hasn’t been found to significantly improve the quality of life. There is therefore a lot of room for improvement of dementia treatments.

Whilst we don’t yet have an adequate treatment for Alzheimer’s, researchers are also looking into diagnosing dementia at its earliest stage. Amazingly, this year, researchers at University College London announced that Sea Hero Quest – a video game they have helped develop – is able to accurately record a subject’s sense of direction and navigational abilities. As these skills are seen to decline during the progression of dementia, it is hoped that a potential diagnostic test could be built from the game, aiming to evaluate navigational skills to diagnose dementia at its earliest stage. This could ensure that patients received the best care possible, as soon as possible, reducing the number of dementia related deaths every year.

 

Hilary Robinson

(Image courtesy of Sea Hero Quest)