Memory: When the filing goes awry
If you think about it, you will see how what we remember is at the heart of how we understand ourselves, connect with others, negotiate the world and even earn a living. Yet, exactly how memory works is a matter of some debate – specialists use metaphors of filing cabinets and supercomputers to illustrate their theories – but what we are certain of is that when our memory is impaired it can disrupt our lives as well as our families. This week we speak with Prof. Saman Gunatilake, Professor of Medicine and Consultant Neurologist at the Department of Medicine, University of Sri Jayewardenepura about how memory works and what to do when it starts to fail.
A person’s memory has multiple constituents, each drawn from a different source. Think of someone you met today – there’s the colour of their hair, the sound of their voice, the pressure of their handshake, there might even be the scent of their favourite perfume or cologne. Each section of this memory is drawn from a different part of the brain and we’re only now beginning to see how it pulls them all together to form coherent thought.
What is widely accepted is the importance of the frontal lobes, temporal lobes and the hippocampus in the brain, says Prof. Gunatilake. These parts of the brain work in unison and it only takes one to be off kilter to generate problems in the system. In an era where MRI and PET scans are allowing us to look inside the living brain and study it as it operates we are beginning to understand more and more about this amazing super computer.
In forming a memory, your hippocampus is flooded with perceptions (sight, scent, taste, texture and sound) fed to it by your array of senses. Along with the frontal cortex, the hippocampus analyses all the inputs it receives and decides which memories are worth storing and these memories become a part of your long term stock. Later they are retrieved with ease – but only if they have been ‘filed’ properly cautions Prof. Gunatilake. Short term memories disappear faster, kept for only as long as they’re useful.
When it comes to memory loss, it’s worth noting that there are in fact different kinds of memories. The memory that allows to you to drive a car, read a book or type a letter (Procedural memory) is different from the memories of what you did yesterday, why you decided to go downstairs and open the fridge or in fact where you left your keys (Declarative memory).
How do you know when memory loss is an issue? After all, who among us hasn’t forgotten where they left their phone or their keys? Found themselves disoriented on a route they’d taken before? Prof. Gunatilake will tell you it’s a matter of degree. If it is interfering with your everyday functioning, making it difficult for you to work or run your usual errands it’s important that you consult a doctor.
Some amount of memory loss and cognitive impairment is natural as we age.
While this is common, it can also sometimes indicate the onset of dementia. Contrary to popular opinion dementia is not a normal part of aging neither is it inevitable- some elderly people remain as sharp as ever even over the age of 80, observes Prof. Gunatilake. A large number of cases of dementia – upto about 70% – are due to Alzheimer’s disease. In a case of Alzheimer’s, the brain shrinks or atrophies, explains Prof. Gunatilake, adding the number of nerve fibres in the brain gradually reduce. Tiny deposits called amyloid plaques begin to form throughout the brain. Amyloid is toxic to neurons. The exact cause for Alzheimer’s is still not known. Symptoms of dementia develop gradually and typically become worse over a number of years, though the pace varies greatly from person to person.
Another important cause of memory loss can be multiple strokes during which the brain is deprived of blood circulation and hence oxygen. This phenomenon, known as vascular cognitive impairment is tied in closely to risk factors like high blood pressure, high cholesterol and diabetes. Smoking, the consumption of excess alcohol and poor exercise routines further add to your risk of having them. This form is called multi-infarct dementia, says Prof. Gunatilake. In effect, a patient has multiple tiny strokes that could go unrecognised. After every infarct more brain damage occurs. Sometimes patients may develop mixed dementia, contracting say both Alzheimer’s and vascular dementia at the same time.
Some people are more vulnerable to developing dementia. Among them are those with a family history of the disease, Down’s syndrome, Parkinson’s disease as well as cardiovascular diseases and severe psychiatric problems. Among the more intangible risk factors are those with a limited social support network or a severe depression.
Multiple other factors can affect the quality of our memory. Physical illness plays a role: an underactive thyroid for instance, can slow down your body’s functions and take a toll on your brain, says Prof. Gunatilake. Athletes like the boxer Mohammad Ali discovered for themselves that trauma to the head can cause memory loss but acute memory loss in the form of amnesia can be brought on by an injury. In fact, memory loss requires careful examination simply because of the host of factors that could cause it – among these are worrying conditions like tumours, infections such as syphilis, alcohol abuse or simpler issues like vitamin deficiencies.
The loss of memory may make it difficult for someone to keep a job, even one they’ve had for a long time or maintain healthy relationships. Unsurprisingly, it can take a heavy toll on an individual’s personality, mood and behaviour. They might be irritable or aggressive, which is why relatives and friends may find it difficult to cope.
Treatments are designed depending on the root cause of the memory loss. In some cases a cure is possible, in others medication and therapy can prevent or at least slow further degradation of your memory. However, because of how slowly dementia can progress, it may be difficult to diagnose. Your doctor might suggest specially designed tests that will explore how good your memory is and examine any causes for concern, says Prof. Gunatilake. Close friends and family may be the first to notice something wrong and encourage the sufferer to seek help.
While medication or surgery are options, a doctor may explore on a case by case basis, simple lifestyle measures can help a little bit. Patients are encouraged to write down and plan their day’s routine so that nothing essential is left undone. Things should be left in common places – say a bowl where important keys can always be found. Certain forms of cognitive stimulation can help keep the brain revved and enhance quality of life. Many doctors recommend regular physical activity, while an array of psychological tools such as cognitive behavioural therapy can also help. It is now known that keeping the brain active, helps to prevent the onset of dementia.
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