When most people have a forgetful moment, they may joke, or even worry, that it’s the start of Alzheimer’s disease or the cognitive decline that can come with age.
But fewer people know in detail how Alzheimer’s disease occurs and functions, how it’s related to mild cognitive decline and why it’s vital that early signs of both are recognised so treatment can be most helpful.
Alzheimer’s is the most common form of dementia, with almost 300,000 Australians currently diagnosed with the condition. According to the latest statistics, dementia, including Alzheimer’s, is Australia’s second-leading cause of death, killing 12,625 people in 2015 alone.
A person is usually said to have early onset Alzheimer’s when they develop the condition in their 20s and by their 40s are severely affected by their symptoms. But Alzheimer’s more commonly appears in older adults, with the risk of developing the condition doubling every five years after the age of 60.
The symptoms can include a loss of short-term memory and other cognitive functions including language, problem-solving, orientation or even attention.
Mood swings, depression and a complete loss of motor function or language can occur in the later stages of the condition.
Symptoms can vary from person to person and can be difficult to identify in earlier stages. A common theme is the existence of memory problems, particularly when recent events are in question. People with Alzheimer’s symptoms can appear vague during conversation and can become less enthusiastic about activities they used to enjoy. Some take longer to complete tasks that were once easy for them, while others struggle to identify people or places.
Mild cognitive impairment shouldn’t be confused with Alzheimer’s, although symptoms of mild cognitive impairment can also emerge early in life. People with mild cognitive impairment do, however, have a higher risk of developing Alzheimer’s or other forms of dementia later.
The most common form of mild cognitive impairment is a condition that significantly impacts memory, but without significant loss of other cognitive functions as there is with Alzheimer’s. For example, a person with mild cognitive impairment might forget names, conversations or appointments, but can typically continue their basic day-to-day tasks unaided.
Their judgment may be affected, in that they’re less able to make sound decisions, or their navigational ability or visual perception may decline.
“Most things that cause dementia have a stage where the person is initially affected mildly, so they would all fit under mild cognitive impairment,” Associate Professor David Darby, a behavioural neurologist at Melbourne Cognitive Services, explains.
Our brains contain tens of billions of neurons, which are special cells that transmit information to different parts of the brain and body using electrical and chemical signals.
In people with Alzheimer’s, this information transfer and process is disrupted because the disease halts communication that should happen between the neurons through tiny gaps called synapses. The disease can also prevent chemicals and nutrients from breaking down within the cells, due to a lack of oxygen and glucose, and this results in neurons being damaged and even dying.
Neurons within the memory parts of the brain are typically most affected during the early stages of Alzheimer’s disease, while the destruction of neurons in the areas that impact social behaviour, language and reasoning develops at a later stage.
Research indicates that people with mild cognitive impairment show the same, but less severe, types of damage to the brain that is seen in people with Alzheimer’s.
In most cases, it will be a family member or loved one who picks up on the symptoms of Alzheimer’s or mild cognitive impairment, rather than the person self-identifying them. Specialists usually conduct cognitive testing (for example, one known as the MMSE) and brain imaging such as MRI or CT scan to help make a diagnosis.
About three per cent of people with Alzheimer’s disease developed the condition due to single gene that runs in their family. Other Alzheimer’s cases can be traced back to lifestyle factors – it has been associated with some preventable health issues – or simply due to advanced age.
Associate Professor Darby explains that health issues involving blood vessels can increase the risk of developing Alzheimer’s.
“What we call vascular risk factors – like high blood pressure, diabetes, high cholesterol, family history, obstructive sleep apnoea – increase wear and tear of blood vessels in the brain and can lead to blood vessel changes, which then lead to cognitive changes”, he says.
The causes of mild cognitive impairment are, like Alzheimer’s, not yet fully understood, but some experts believe the risk factors are the same as those of Alzheimer’s: old age, a family history of mild cognitive impairment, Alzheimer’s or dementia, and the prior existence of vascular conditions.
The development of Alzheimer’s and mild cognitive impairment has also been linked to a build-up of what’s called amyloid protein in the brain and in the blood vessels of the head, and to another protein called tau that can form abnormal clumps in the brain.
Some people have genes that increase their amyloid protein, and all people over the age of 75 have clumps of tau protein present in the temporal lobes of their brain (the part of the brain that processes sensory inputs).
“In the presence of excess amyloid protein, these tau clumps can spread into other parts of the brain correlated with progression of symptoms such as making decisions, using language, causing word-finding difficulty and hesitations, or with spatial function, causing problems such as getting lost.” Associate Professor Darby says.
Researchers are now working with patients who aren’t yet showing Alzheimer’s symptoms in the hope they can remove amyloid proteins to prevent the onset of Alzheimer’s, but this research is at an early stage. In patients who are already showing symptoms, being diagnosed as soon as possible could help prevent their condition from deteriorating further.
“If someone has no symptoms, then there’s no recommended treatment at the moment,” Associate Professor Darby explains.
“We would recommend that if people somehow find out they’ve got amyloid in the brain, they try and get involved in some trials to see if some of the experimental treatments might work. If they do have mild symptoms and their doctor thinks it’s related to Alzheimer’s disease in an early stage, there are trials of promising therapies and we’re very actively seeking people for these.”
For people with mild memory problems due to mild cognitive impairment or Alzheimer’s, evidence has shown that both lifestyle and dietary treatments can slow the rate of decline in cognitive skills.
“There have been a number of studies which have shown that exercise, and particularly aerobic exercise of about 30 minutes, three to four times a week as a minimum, slows the rate of decline in people with mild memory problems,” Associate Professor Darby explains.
“Aerobic exercise means getting up a sweat and increasing your heart rate (if that’s safe for your heart to cope with that) and we normally recommend bicycle riding, for example with an exercise bike, rowing, swimming or jogging if you can do these.”
Dietary changes have been shown to delay cognitive decline in many patients. For example, a so-called Mediterranean diet that’s rich in fruits, vegetables, olive oil, beans, wheat and rice, and limited in red meats and poultry can maintain brain power and delay many symptoms associated with Alzheimer’s.
“A Mediterranean diet, for someone who has a Mediterranean diet from early adult life onwards, has been associated with a decrease of overall dementia,” Associate Professor Darby says.
Meanwhile, foods rich in omega-3 fatty acids, B vitamins and antioxidants are known to contribute to better brain health. Eating, for example, salmon, cod or tuna twice a week can be beneficial to memory, while consuming a serve of leafy green vegetables each day can also promote brain health.
It can be difficult to consume these levels of nutrients naturally, but products such as medical nutrition drink Souvenaid® are proven to help those with milder cognitive problems delay the decline in their skills. For example, a 125millilitre bottle of the drink each day includes the same nutrients as eating eight tins of tuna, 1 kilogram of tomatoes, 100 grams of minced beef, four eggs, 1.2 kg of broccoli, 710g of spinach, one orange and a handful of Brazil nuts.
“The bottle contains a concentrate of really, effectively, a Mediterranean diet,” Associate Professor Darby says. “It has fish oil and things like choline and various vitamins and UMP (uridine monophosphate). All of these things are important if you’re going to make new membranes in the brain.”
Souvenaid® is a Food for Special Medical Purposes for the dietary management of the early stages of Alzheimer’s disease. Souvenaid® must be used under medical supervision. You must seek advice from your doctor, nurse or pharmacist if you are unsure of your condition or diagnosis or if you would like to use Souvenaid®.
Souvenaid® nutritionally supports memory function in the early stages of Alzheimer's disease (must be used under medical supervision).
If you are concerned about your cognitive health, please see your Healthcare Professional.