Causes of Memory Loss
As we get older it is not uncommon to be aware of a slight deterioration in memory. For the majority of individuals this amounts to no more than slight forgetfulness and does not progress to cause any significant impact on the ability to perform everyday tasks.
The onset of dementia due to, for example, Alzheimer’s disease is an insidious process and may go unrecognised for months, or even years. This is partly because of the fact that a change in cognitive status is a recognised, and even expected, consequence of normal ageing.
Some people do experience a progressive decline in their memory and other brain functions and eventually develop dementia. It is important to remember that many conditions can cause an upset of the memory and that not all individuals who have memory impairment have dementia.
For example stress or anxiety, fatigue, physical illness, medication, alcohol and bereavement can all have an adverse effect on memory function. It is important therefore not to jump to conclusions.
Individuals who are experiencing memory impairment should be assessed at an early stage to enable early identification of the underlying cause.
Glasgow Memory Clinic offers a free memory screening service for those over 50 who are concerned about memory decline and who are potentially interested in participating in our research program. Contact us for more information.
A decline in cognition is a natural part of the normal ageing process. This is characterised by a failing memory and is an accepted part of getting older.
As a consequence, it can sometimes be difficult to distinguish between the memory loss associated with normal ageing and the very early stages of dementia. It is now accepted that there is an intermediate stage, known as mild cognitive impairment (MCI) that falls along the continuum between normal ageing and dementia.
Many people with MCI develop increasing difficulty with memory but this has relatively little impact on their way of life. Often the symptoms of MCI are assumed to be those expected during the normal ageing process.
The normal memory changes associated with ageing are characterised by momentary lapses in memory such as misplacing objects, difficulty remembering names and forgetting appointments. In MCI, the memory loss is greater and problems with the thinking process more pronounced. MCI sufferers can find it more difficult to remember details after a relatively short period of time, and may forget important events, e.g. family birthdays.
This kind of information tends to be retained during normal ageing. In contrast, the abnormal memory loss in dementia is accompanied by other problems such as disorientation, inability to recall very recent events and confusion.
The importance of identifying MCI is becoming increasingly accepted with the recently described conditions of Prodromal Alzheimer’s disease that can now be diagnosed using new biomarker tests. It provides the opportunity for monitoring of memory function and early treatment should the individual subsequently develop dementia. Expert assessment of individuals complaining of memory decline will usually be performed in a memory clinic.
Glasgow Memory Clinic offers a free memory screening service for those over 50 who are concerned about memory decline and who are potentially interested in participating in our research programme. Contact us for more information.
Some patients with mild cognitive impairment are in the very early stages of Alzheimer’s disease called Prodromal Alzheimer’s disease. In this condition there is mild cognitive impairment and also positive biomarker tests that indicate underlying Alzheimer’s disease as the cause of memory impairment. The biomarker tests may be a protein measured in the spinal fluid or a special brain scan (PET scan) designed to detect amyloid protein deposits in the brain. Prodromal Alzheimer’s disease has been recently described and the importance of identifying this condition is recognised by the international research community.
Every case of Alzheimer’s disease is likely to follow a unique course and manifests itself in different ways. This makes diagnosis, initially, difficult. There is now increasing emphasis on early diagnosis and memory clinic services are now becoming an integral part of health care services in many countries.
The disease is a progressive one. Early signs of the onset of the syndrome may include a number of the following symptoms: Memory impairment which is often one of the earliest symptoms, growing confusion over names, appointments and recent events; dramatic mood swings for no discernible reason; increasing withdrawal from those around them and a lack of confidence. As yet no cause has been identified for the onset of Alzheimer’s disease.
There is some evidence that genetic inheritance has some bearing on the likelihood of any individual developing the disease. A number of theories, such as exposure to aluminium being a factor in the onset, have now largely been seen as without foundation.
One factor that has clearly emerged in the development of Alzheimer’s is age.
The prevalence of the dementia moves from one in 20 in the over 65s to one in 5 in the over 80s.
Although the factors that trigger the disease remain unclear, there is increasing understanding of its physical manifestations. According to the pioneering work of the neurologist Alois Alzheimer, who first identified the syndrome, as the disease develops plaques and tangles develop in the brain structure. This is thought to cause progressive death of brain cells, leading to the mental impairment outlined earlier. Although there is no cure currently available it is known from autopsy studies that the chemical messenger acetylcholine is often depleted in patients with Alzheimer’s disease.
This knowledge has led to the development of treatments that aim to boost acetylcholine levels in the brain. There are currently three drugs available for the specific treatment of mild to moderately severe Alzheimer’s disease. These drugs are the acetylcholine esterase inhibitors Aricept (Donepezil), Exelon (Rivastigmine) and Reminyl (Galantamine).
These treatments may retard the progression of the symptoms of the disease.
The drugs are symptomatic treatments and at this time are not thought to modify the underlying disease process. They can, however, lead to significant improvements in cognition and memory, ability to perform daily tasks and in some cases can alleviate difficult to control behaviour.
Cerebrovasular disease is a term often used to describe ‘hardening of the arteries’ in the brain. It is thought that this results in poor circulation of blood to parts of the brain and deterioration in mental abilities. Unlike in cases of Alzheimer’s disease, sufferers from vascular dementia may experience damage to only distinct parts of the brain, rather than impairment of all functions. Also, unlike Alzheimer’s, the root causes of vascular dementia are far more clearly understood.
The most common cause of an onset of the syndrome is a stroke. A number of factors, mostly lifestyle-related, contribute to the likelihood of any individual suffering from a stroke. Raised blood pressure (hypertension), dietary factors, raised cholesterol levels, cigarette smoking and excessive alcohol consumption can increase an individual’s vulnerability to a stroke.
A stroke usually takes place when a blood clot forms and the brain suffers a loss of its oxygen supply. This results in the irreversible destruction of parts of the brain. A stroke may cause the sudden loss of speech, paralysis or numbness and co-ordination problems.
Some patients who have suffered a stroke go on to develop memory impairment which can progress to vascular dementia.
Vascular dementia is more common in some countries than others. In the U.K it is thought to account for about 25 per cent of all dementia cases. As well as only affecting certain parts of the brain, vascular dementia differs from Alzheimer’s in a number of other key ways.
Sufferers from vascular dementia may show a much more gradual decline than those with Alzheimer’s. This can include extended “plateau” periods where no deterioration occurs. There is a tendency for vascular dementia sufferers to retain a greater degree of self-awareness. This can induce periods of depression as the patient becomes aware of their own deterioration.
Despite the similarities in some of the symptoms, it is vital that the correct form of dementia is diagnosed. This is due to the vastly differing treatments available for the two syndromes. Physicians try to identify and modify risk factors such as blood pressure, smoking, alcohol, cholesterol and fat levels with the aim of preventing further strokes therefore preventing the development of vascular dementia.
Parkinson’s disease (PD) is found worldwide and in every ethnic group where studies have been conducted. Celebrity sufferers – such as the boxer Muhammad Ali – and the highly visible nature of the symptoms have raised awareness of the condition in many countries. Memory impairment and a decline in general cognitive function occur in many patients with PD. Indeed some patients are diagnosed as suffering from coexisting Alzheimer’s disease.
The condition was first identified by Dr James Parkinson in 1817. At the time it was termed “the shaking palsy”. Parkinson’s description of the disease refers to its most highly visible element – the tremor. This occurs when the patient is at rest and is typified by involuntary movement of the arms and legs. The tremor becomes gradually worse as the patient deteriorates.
Two other symptoms are commonly held to define PD – rigidity and slow movements. The rigidity results in dramatic loss of flexibility. The slow movement is characterized by the shuffling walk often associated with PD sufferers, as well as other loss of motor control and dexterity.
The cause of Parkinson’s disease remains unknown. It is known that in PD there is a shortage in the production of the neurotransmitter dopamine. Other neurotransmitters such as acetylcholine, noradrenaline and serotonin are also affected in some patients with PD. At present there is no cure for PD. The main stay of treatment is to try and replace the depleted dopamine levels by administering L-dopa or giving drugs that prevent the breakdown of L-dopa (COMT inhibitors). The exact cause of the failure to maintain the dopamine balance is unknown. However, a number of factors – including heredity, head injuries and exposure to certain toxins – have been mooted.
The progress of the disease has been characterized of featuring an “on/off” process, periods where therapy and medication prove ineffective against the disease. There is growing interest in the use of the ‘anti- Alzheimer’ drugs (acetylcholinesterase inhibitors) and antidepressants such as the selective serotonin re-uptake inhibitors as patients may have coexisting memory failure and depression.
Some advances in surgical procedure such as the transplant of foetal cells to replace the damaged dopamine producing cells have led to hope that a cure may eventually be developed, but this is, as yet, not on the immediate horizon.
Memory impairment is often a feature of depression. Depression occurs not infrequently as we get older. There are many reasons for this such as loneliness, physical ill health or physical changes within the brain causing a reduction in certain chemical messengers.
The common symptoms of depression are those of a depressed mood, loss of interest and loss of energy. Other symptoms may include reduced concentration, reduced self esteem, guilt feelings, pessimism regarding the future, altered sleep and decreased appetite.
An individual suffering from depression may also complain of memory impairment. Sometimes this is simply due to depression; in other instances it may indicate co-existing dementia.
It is important therefore to consider if someone is depressed if they have memory impairment. Conversely if someone has memory impairment it is important to consider if they have depression.
The reason for this is that many treatments are available for depression. If depression is identified and successfully treated the symptoms of memory impairment if present may be resolved.
In addition, should the individual with depression go on to develop progressive memory failure and dementia, this will be identified at an early stage and allow early treatment of the dementia.
Whilst details have been given of the common conditions that can cause memory impairment there are of course other conditions that can cause an upset of the memory.
To consider these at this point in time is beyond the scope of this site. If you do have concerns about your own memory or that of someone you know you can discuss this
with your own doctor.