Alzheimer’s Disease: Types, Symptoms, Causes and PET-CT as a Diagnostic Tool

Alzheimer's disease is a case of change that happens in the brain and causes the changes in memory, thinking, learning and behaviour. It's the most prevalent type of dementia and can cause an increasing sense of difficulty with everyday tasks over time. While more often seen in older adults, Alzheimer's disease doesn't happen to everyone as they get older.

Early identification of the Alzheimer's indicators can facilitate patients and their families to look for medical advice, looking at options for care and making plans for the future. To explore abnormalities in brain function and brain structure, physicians may consider taking some blood tests, imaging tests of the brain, and in some cases, imaging tests with PET (positron emission tomography). Diagnostic imaging services at Molecular Diagnostics and Therapy aid in the assessment of different medical conditions and allow the doctor to collect information when formulating plans for additional investigations.

What Is Alzheimer’s Disease?

Alzheimer’s disease is a progressive neurological disease that causes damage to brain cells. As the disease progresses, it will cause damage to connections within the brain. It affects memory first and then other areas of the brain responsible for language & reasoning, judgement & decision-making. This can cause difficulties with remembering conversations, recent events and places, knowing how to do certain tasks, and the inability to do certain things for oneself.

Unlike forgetful moments, some of which everyone experiences throughout life, Alzheimer’s disease is a different pathology. However, if these problems continue or worsen and cause trouble with your memory, it is important to have them checked by a health care provider. Early assessment can help determine what may be causing the person to have problems with memory and thinking, and rule out other conditions that might be causing these problems.

Alzheimer’s Symptoms

Typically, Alzheimer's symptoms start slowly and over time begin to become more evident. Signs and symptoms and their development differ in patients. Common symptoms include:

Memory loss: Forgetting recent events, repeating questions, or frequently misplacing everyday objects.

Difficulty planning: Struggling to manage finances, organise tasks, follow instructions, or solve familiar problems.

Language difficulties: Having trouble finding the right words, following conversations, or explaining thoughts clearly.

Confusion about time and place: Forgetting dates or becoming disoriented in familiar surroundings.

Changes in mood and behaviour: Experiencing increased anxiety, irritability, apathy, or unusual emotional responses.

Difficulty performing daily activities: Finding familiar tasks, such as cooking, shopping, or managing medicines, increasingly challenging.

As Alzheimer’s disease advances, patients may require greater support with personal care and everyday decisions. Sudden confusion, however, is not typical of gradually progressing Alzheimer’s disease and needs urgent medical assessment because it may indicate another medical problem.

Alzheimer’s Causes and Risk Factors

We don't yet know what causes Alzheimer's disease. It is thought to be caused by a combination of genetic, biological, and environmental factors. Alzheimer's progresses with the formation of two proteins, amyloid-beta and tau. Abnormal buildup of Tau can result in tangles within the cells, and amyloid beta can get trapped between brain cells in plaques. These changes are linked to damage to brain cells and impaired communication between them. There are several potential risk factors for Alzheimer's disease.

Age: Increasing age is the strongest known risk factor, although Alzheimer’s disease is not an inevitable consequence of ageing.

Family history and genetics: Having a close relative with Alzheimer’s may increase risk. Certain genetic variants, including APOE-e4, are associated with increased risk but do not guarantee that someone will develop the disease.

Cardiovascular health: High blood pressure, diabetes, high cholesterol, smoking, and physical inactivity can affect overall brain health and may contribute to cognitive decline.

Previous head injury: Certain serious head injuries have been associated with an increased risk of dementia.

Other memory problems may be caused by a deficiency of vitamins, changes in thyroid function, side effects of medication, depression, or sleep disorders. Medical testing can aid in determining these possibilities.

Types of Alzheimer’s Disease

Alzheimer’s disease can be described according to the age when symptoms begin and the genetic factors involved.

1. Early-Onset Alzheimer’s Disease

Early-onset Alzheimer’s refers to when the disease develops at a younger age (<65 years). This occurs at a much younger age than late-onset Alzheimer’s (40s/50s patient age) and occurs less frequently. Some cases are due to an inherited mutation in the genes; however, many cases are non-genetic.

2. Late-Onset Alzheimer’s Disease

Late-onset Alzheimer's disease is the more typical case and typically occurs when individuals reach the age of 65 and beyond. There are many factors: age, genetics, and general health.

3. Familial Alzheimer’s Disease

Familial Alzheimer's disease is when a family history of Alzheimer's disease exists. An autosomal dominant form of Alzheimer's can appear at an earlier age and is caused by rare inherited mutations. But simply having a family history isn't enough to cause the disease, though.

How Is Alzheimer’s Disease Diagnosed?

Unfortunately, there are several steps in the diagnosis of Alzheimer's since no one test will work for every person. Generally, symptoms, medical history, medications, and functioning in daily life are reviewed first. There are tests of memory, attention, language, and problem-solving functions. Bloodwork can help to determine the presence of other factors which may affect cognition. To check the structure of the brain and to see if there are other causes, such as a stroke, bleeding, or a tumour, an MRI or CT scan might be performed.

Doctors might suggest specialised tests for the changes in the body associated with Alzheimer's disease in certain patients. These might include a PET scan or, as appropriate, other biomarker tests. Depending on clinical assessment and the patient's symptoms, as well as whether the result might affect the diagnosis or treatment, a choice between methods is made.

PET-CT for Alzheimer’s Disease: What Does It Show?

PET imaging can give information on brain activity or on certain specific changes in the brain which may indicate Alzheimer's disease.

FDG PET Imaging

FDG PET scan shows patterns of brain glucose use. Brain cells consume glucose for energy; some brain diseases can cause characteristic decreases in brain metabolic activity. Identifying these patterns and trends can guide physicians in their investigation of cognitive decline when a diagnosis is unclear.

Amyloid PET Imaging

Special amyloid tracers identify amyloid plaques in the brain with Amyloid PET. It might assist in deciding, in some patients, whether significant amyloid deposition occurs or not. But just having an amyloid scan doesn't necessarily mean that their symptoms are attributed to Alzheimer's disease.

Tau PET Imaging

Tau PET involves the use of specialised tracers to aid in the diagnosis of abnormal tau build-up. This is not always available and may not be needed for all patients. PET-CT scans for Alzheimer’s disease are not always required however may be used if further information is required by a specialist. Symptoms, cognitive testing, medical history, and other investigations will need to be considered along with the results.

Diagnostic imaging services are available at Molecular Diagnostics and Therapy to help diagnose certain medical conditions. This should be discussed with your neurologist or treating physician to decide which investigation is required. Certain tracers for brain PET scans will need to be checked for availability with the diagnostic centre.

Conclusion

Alzheimer’s disease is a progressive disease that can affect the brain, leading to problems with memory, thinking, and daily living. Knowing the symptoms, causes and types of Alzheimer’s can help families recognise any changes and receive the correct medical advice. Clinical assessment and cognitive testing are key.

MRI, CT and specialised PET scans may be used to gain more information. PET-CT scans for Alzheimer’s disease are not always needed and should only be recommended if required for the individual’s medical needs. Diagnostic imaging services are available at Molecular Diagnostics and Therapy to help diagnose certain neurological conditions. If you or a family member are experiencing ongoing or worsening memory issues, please speak to a qualified healthcare professional for the correct assessment.