Progressive Supranuclear Palsy and Alzheimer's Disease are both neurodegenerative disorders that result in the gradual loss or damage of nerve cells in the brain. However, they both possess distinct differences in terms of symptoms, underlying causes and progression. In this article, the symptoms, diagnostic methods, and treatments of both Progressive Supranuclear Palsy and Alzheimer’s Disease are discussed. 

What is progressive supranuclear palsy?

Progressive Supranuclear Palsy (PSP) is a rare, neurological condition that is primarily caused by damage to nerve cells in the brain. This damage is caused by the build-up of a protein called TAU. The function of TAU is to support the structure of nerve cells and transport important materials in the brain. However, in progressive supranuclear palsy, TAU builds up and forms tangle-like structures inside the nerve cells. These ‘tangles’ affect the function of nerve cells, causing problems with body movements, eye movements, balance, and speech.¹

Symptoms of progressive supranuclear palsy

The symptoms of PSP can vary among different populations and tend to develop gradually, depending upon several factors. Symptoms can be classed into three categories: early symptoms, mid-stage symptoms, and advanced symptoms.²

Early-stage symptoms consist of problems with body movements including

• Stiffness, 
• Slowness of movement, and 
• Poor balance, which leads to frequent falls. 

There can also be problems with eye movements including not being able to focus on objects, having blurred vision and being unable to keep eye contact for a long time. There can also be changes in mood and/or behaviour, including lack of motivation and depression.^2,3

Mid-stage symptoms involve the early stage symptoms of PSP becoming more prominent as well as the development of new symptoms. These new symptoms can comprise speech and language changes, including slurred speech, which is medically known as dysarthria. There can also be problems with swallowing, also called dysphagia. An inability to control the eyelids and trouble holding gaze are other common symptoms.²

Advanced symptoms develop when existing earlier-stage symptoms continue to worsen. Memory disturbances can also occur that signify dementia, and problems with bowel and bladder functions might be observed. Additionally, constipation and difficulty passing urine are also common.²

Diagnosis of progressive supranuclear palsy

The diagnosis of PSP is challenging as its symptoms resemble those of Alzheimer’s Disease and Parkinson's Disease. Hence, diagnosis is usually based on the specific pattern of a patient’s symptoms and by ruling out other conditions. Physical examinations to assess motor function, eye movements, balance and cognitive abilities are undertaken. Brain scans, such as magnetic resonance imaging (MRI) and positron emission tomography (PET) scans, are also undertaken to assess underlying changes that may accompany PSP. These changes may include shrinkage in certain regions of the brain and the presence of abnormal deposits, such as that of TAU ‘tangles’. Neuropsychological testing can also be carried out to evaluate the full extent of symptoms and their impact on mental abilities such as memory, concentration and interpretation of language.⁴

Treatment of progressive supranuclear palsy

Although there is no specific cure for PSP, there are many things that could be done to help manage the symptoms of PSP. Different health and social care professionals can work together to help manage the symptoms, including neurologists, physiotherapists and speech and language therapists. Neurologists are doctors who specialise in diagnosing and treating diseases of the nervous system, physiotherapists can help individuals recover from injuries and improve their physical health, and speech and language therapists help individuals recover from communication and swallowing disorders.⁵

Medication, such as Levodopa may also be taken by individuals affected by PSP.⁵ Levodopa is a medication typically used to treat Parkinson’s Disease by increasing levels of dopamine, a chemical messenger, in the brain. However, a subgroup of people affected by PSP experience Parkinson-like symptoms, including a tremor, stiffness and rigidity.⁶ In these individuals, Levodopa can produce beneficial effects on these symptoms. Such individuals may also be given Levodopa before meal times to aid with feeding and swallowing.⁷ 

What is alzheimer’s disease?

Alzheimer’s Disease (AD) is a type of dementia that affects a person’s memory, thinking and behaviour. Similarly to PSP, AD is assumed to be predominantly caused by the abnormal buildup of the protein tau, amongst other proteins, within nerve cells. The buildup of tau results in the dysfunction of nerve cells, leading to damage and loss of cells. Multiple factors are thought to increase a person’s risk of developing AD. These factors include

• Age, 
• A family history of the condition, 
• Untreated depression, and 
• Lifestyle factors⁸

Symptoms of alzheimer's disease

The symptoms of AD progress slowly with age, however, people who experience serious infections or take certain medications can expect to see their symptoms progress at a faster rate than expected. The symptoms of AD can also vary between different people depending upon factors. They can also be classed into three categories: early symptoms, mid-stage symptoms and advanced symptoms.⁹

The early-stage symptoms emerge as subtle memory issues such as forgetting the names of places and people and misplacing items. Problems with completing familiar tasks and issues with speech and language are also quite common.⁹

The middle-stage symptoms occur as the early-stage symptoms become more prominent and new symptoms begin to develop. These new symptoms can consist of getting lost in familiar places, changes in mood and mood swings, depression and even hallucinations. At this stage, a patient diagnosed with AD will most likely need assistance with everyday activities.⁹

At the stage of advanced symptoms, the existing symptoms become increasingly heightened. Difficulty eating and swallowing, severe weight loss and significant memory loss are observed in patients. At this stage, patients must be provided with full-time assistance with their daily activities.⁹

Diagnosis of alzheimer's disease

There is no single test for the diagnosis of AD so a combination of methods may be performed by a healthcare professional. They may look through a patient’s complete medical history and ask about any symptoms that they may be facing and they can also carry out tests such as blood tests. To further assess symptoms and assess the function of the different areas of the brain, a patient could be referred to a neurologist or psychiatrist. To further aid diagnosis cognitive tests may be performed, which include a number of different tasks to assess mental abilities such as short- and long-term memory and language and communication skills. Brain scans, such as computer tomography (CT) scans and magnetic resonance imaging (MRI) scans, also be carried out to look for potential brain changes occurring as a result of Alzheimer's Disease.⁸

Treatment of alzheimer's disease

Although there is no specific treatment for AD, several medications such as acetylcholinesterase inhibitors and memantine are given to patients to aid their symptoms. Acetylcholinesterase inhibitors, such as donepezil and galantamine, increase the levels of acetylcholine, a chemical messenger that transmits signals between nerve cells and regulates various functions such as attention and cognition. On the other hand, memantine blocks glutamate receptors found in the brain. Glutamate is a chemical messenger also involved in the transmission of signals between nerve cells and has a role in memory and learning. Excessive activation of the glutamate receptors can lead to damage and death of nerve cells. Hence, memantine acts to reduce the activity of glutamate receptors to protect nerve cells. Memantine can also be used in combination with donepezil to enhance its effects when treating moderate to severe levels of AD. However, as with all medication, common side effects include headaches, dizziness, and fatigue.^11,12

Summary

In summary, both PSP and AD are neurodegenerative disorders that affect the brain, however, they both have different underlying mechanisms and symptoms by which they can be distinguished. PSP is a rare degenerative disorder that is characterised by symptoms such as stiffness, slowness of movement and irregular eye movement, whereas AD is a more common disorder that is associated with memory loss and cognitive decline. PSP and AD share some similarities including the loss of nerve cells in the brain following tau protein accumulation and they are both associated with memory loss and dementia. However, their underlying causes and symptom progression differ. Moreover, the method of treatment and diagnosis varies between the disorders and is based on an individual basis. Understanding these differences is important for diagnosing and treating these conditions.