Alzheimer's Disease

Alzheimer's disease is a medical condition caused by changes in the brain. [1] Alzheimer’s disease is the most common type of dementia, and about 25,000 new cases are diagnosed each year in Canada. [2] It can affect memory, behaviour, problem-solving skills and daily activities. The changes in the brain can occur up to 20 years before the first symptoms develop. [1]

Alzheimer’s disease is thought to be caused by changes in two proteins: beta-amyloid and tau. [1] These two proteins are currently one area of focus of many researchers who are aiming to find treatments that could potentially slow or stop Alzheimer’s disease. A healthy brain is made up of neurons which send and receive signals to and from the brain and are responsible for carrying information throughout the body. The signals transmitted by neurons form the basis of our thoughts, memories, and feelings.

In people with Alzheimer’s disease, amyloid builds up causing ‘plaques’ between neurons and tau proteins form ‘tangles’ inside neurons. [1] Over time, the build up of beta-amyloid reaches a tipping point and causes the spread of tau tangles throughout the brain. [5] These ‘plaques’ and ‘tangles’ block neurons from sending and receiving signals and cause neurons to die, and the brain to shrink. [1]

One of the first regions of the brain impacted by Alzheimer’s disease is the hippocampus – which has a vital role in forming memories. [3] The death of neurons in the brain leads to memory loss, difficulty making decisions and language problems. As the disease progresses, these symptoms slowly get worse over time. [4]

Alzheimer’s disease can be divided into three main stages:[5-7]

• Stage 1: People at risk for progression to Alzheimer's disease is the first stage of the disease, where changes are occurring in the brain but the person does not have obvious symptoms.[5]
• Stage 2: In Prodromal Alzheimer’s disease, also called Mild Cognitive Impairment (MCI), there are small changes to a person’s abilities or behaviour, which become more obvious over time.[6]
• Stage 3: Alzheimer’s dementia is the final stage of the disease where the person needs more help in carrying out their usual daily activities, and they can end up relying on nursing care or a family carer.[7]

Alzheimer’s progresses differently in everybody and over many years. The disease spreads to other parts of the brain. [3] Symptoms slowly get worse over time. This figure outlines some of the symptoms that occur during Alzheimer’s.

Scientists are still working to understand exactly what causes Alzheimer’s, but we know that the greatest risk factor is age. Genetics, lifestyle and environmental factors may also contribute to someone's likelihood of developing Alzheimer's [1].

Risk factors are aspects of your lifestyle, environment and genetic background that increase the likelihood of getting a disease. Risk factors on their own are not causes of a disease. Rather, risk factors represent an increased chance, but not a certainty, that dementia will develop.

Many of these risk factors are non-modifiable, or factors you cannot change such as [8]:

• Age – the biggest risk factor for Alzheimer’s disease is increasing age.
• Genetics – some genes are associated with a higher risk of Alzheimer’s disease.
• Positive family history – the risk is a bit higher than normal if a parent or brother/sister is affected.
• Gender – Alzheimer’s disease is more common in women.

There are also risk factors for Alzheimer’s disease that are modifiable, or you change. These include [9]:

Research suggests that 40% of dementia cases are preventable by actively taking steps to lead a healthier lifestyle. [9] A healthy diet, good sleep and regular exercise may help to protect against Alzheimer’s disease. [9] Mental stimulation, and social activity have also been linked to better brain health. [9]

Diagnosing Alzheimer’s disease can be complicated.  Diagnosis involves a combination of tests including cognitive tests performed by a doctor or psychologist, as well as physical evaluations, blood tests and imaging. The cognitive tests are designed to measure memory, concentration span, communication and orientation, amongst others. [10]

But the diagnoses made based on the results of these tests are only accurate 70-80% of the time. [10] This is because some of the results can be skewed by factors such as the lack of sensitivity and specificity of the tests. In most cases, structural brain scans like computerised tomography (CT) scans are also used to rule out other causes, which may be indicative of Alzheimer’s Disease. [10]

Today, new tests are being developed that could provide additional information to support an earlier diagnosis. These are designed to search for tell-tale signs of Alzheimer’s in the blood or cerebral spinal fluid, known as biomarkers.[11] These are mainly used for research purposes today. [12]

The earlier Alzheimer’s is detected and diagnosed, the better. Detecting Alzheimer’s disease early allows you to:

There is an immense amount of research to create early diagnostic tools and treatments related to brain health and aging from the lab to the point of care. One organization that’s leading the way is Cogniciti.

Cogniciti has developed an online brain health assessment. The purpose of the assessment is to learn more about your memory and attention, and let you know if you should see your doctor for further assessment.

Note that this test does not provide a diagnosis, medical advice or treatment.

*Cogniciti's website and tools should not be construed as medical advice, diagnosis, treatment, or the provision of health care. They are not a substitute for advice from a health care professional. Always seek advice from your doctor or other qualified professional if you have any questions about your brain health.