Mild Memory Loss and its Assessment

Mild memory loss is also known as mild cognitive impairment or MCI. It is a common phenomenon which affects all of us at times. It is not the same as dementia.

The challenge for the GP is to recognise more serious memory loss - reported by the patient or by a relative - which may be a precursor of overt dementia. The National Institute for Clinical Excellence (NICE) recommend that early assessment should take place, to enable planning for the future or, if treatment is to be given, to enable its institution at an early stage. They also recommend that a memory assessment service should be the single point of referral for all patients with a possible diagnosis of dementia.¹ NICE have recently produced commissioning guidance, which emphasises the need for intergrated and quality-assured local memory assessment services.²

It is difficult to obtain accurate figures as not everyone with decline of memory will present with symptoms. Women and individuals with low educational achievement have a higher frequency of memory complaints.³ Many older people complain of mild memory loss, and do less well than their young counterparts in tasks which assess memory. It is assumed that mild memory impairment is a common, even normal consequence of the ageing process. Longitudinal studies in the elderly have revealed a gradual decline in the cognitive abilities of older people, but differences between individuals in the rate of decline suggest that at least some of this age related deterioration is due to the inclusion of subjects with incipient dementia.⁴ The suggestion that elderly people may demonstrate an incipient phase for Alzheimer's Disease (AD) is supported by studies in the elderly which have shown evidence of AD years before clinical symptoms are evident, and this is more common in individuals with memory impairment.⁵ Although mild memory impairment is very common in the ageing population, it becomes abnormal when it has an impact on a person's ability to function normally on a day to day basis.

An individual may present complaining of loss of memory but very often it is not the patient but a family member who makes the complaint. This may cause some difficulty for the doctor if the patient is reluctant to admit that there is a problem. Whilst the autonomy of the individual is to be respected, forgetfulness may put both the patient and others at risk. Forgetting to turn off a cooker or a fire at night may cause a fire. Leaving the gas on but unlit may cause an explosion. A common cause for concern is the ability to drive. This is discussed in Help and Advice for Relatives of Demented Patients.

Assessing memory loss

A number of tools are available, as follows:
The Mini Mental State Examination (MMSE) - this was developed by psychiatrists, and is widely regarded as the 'gold standard' test for dementia.
6 Item Cognitive Impairment Test (6CIT, the Kingshill test) - this was developed in 1983 3 by regression analysis of a more detailed assessment, the Blessed Information Memory Concentration Scale (BIMC).

The Abbreviated Mental Test Score (AMTS) - this was developed by geriatricians, and is probably the best known test in general hospital usage.
The 6CIT is probably the best compromise between specificity, sensitivity and ease of use. The validity of the AMTS has been questioned in the multicultural environment of primary care, but can be adapted for use in such a setting.⁶
For more information, see Screening for Dementia in Primary Care.

Although some decline in memory may be seen as normal with advancing years, it may also be due to other factors and they may be treatable although this is by no means true of them all. By far the commonest cause of significant impairment of memory is AD and although it is characteristically a disease of old age, it can strike quite young. Mild impairment can precede serious cognitive disfunction by many years.⁵ Some of the other dementias also tend to strike in middle age. Around the menopause, some women get forgetful and make lists to remind themselves.
There are many factors that may influence cognitive decline:⁷

• Stroke
• Hypothyroidism
• Hyperparathyroidism
• Hypoperfusion
• Head trauma, including recurrent trauma of having been a boxer
• Open heart surgery with cardiopulmonary bypass
• Medication use
• Hepatic impairment
• Depression
• Drug or alcohol abuse
• Toxins, infections, metabolic and structural causes

More subtle causes which may be present in a large proportion of the elderly, and not so elderly population include:

• Oestrogen decline - there is evidence that postmenopausal oestrogen levels have a negative correlation with risk of cognitive decline⁸
• ACE inhibitors and angiotensin II antagonists - may improve cognitive function in the elderly⁹
• High corticosteroid levels in older people - associated with cognitive decline¹⁰
• Testosterone decline - may be relevant but evidence is not strong¹¹
• Mesiotemporal sclerosis

There are many causes of dementia and in the early stages they will present with mild memory loss. The following list is far from all inclusive:

• About 20% of patients with Parkinson's disease (PD) also develop dementia
• Dementia with Lewy bodies is second only to AD as a common cause of dementia
• Pick's disease (fronto-temporal dementia)
• Huntington's chorea
• Syphilis
• AIDS
• Multiple Sclerosis
• Creutzfeldt-Jakob disease
• Heavy metal and carbon monoxide poisoning

A complaint of impaired memory is common and may or may not be pathological. A stepwise approach to investigation is required.¹² Routine investigations to assist in ruling out physical causes should include:

• Full history, especially with respect to past medical history, family history, drug and social history
• Full examination looking especially for possible cardiac or neurological abnormalities
• An assessment of cognition using one of the tools outlined above
• Laboratory tests - FBC, urea and electrolytes, liver function tests, calcium and vitamin B12 level, thyroid function tests, random or fasting blood sugar

The assessment of memory impairment which is not associated with any physical illness or structural abnormality relies on specialist tests which assess function independently of structure and may include:

• Neuropsychological testing
• Electroencephalogram and evoked potentials
• Functional imaging, CT scan, PET scan, MRI scan, magnetoencephalography

The Alzheimer's Society recommend the following non-drug strategies to cope with memory loss:¹³

Coping with everyday life

• Keep track by making ‘to do’ lists of tasks.
• Break up tasks into bite-sized chunks to make them more manageable.
• Try to do one thing at a time – tackling too many things at once can be confusing.
• Try to have a routine to give structure to your day and help you remember what you are supposed to be doing.
• Take your time – there’s no hurry.

Memory aids

• Use clocks, wear a watch, put up a calendar and think about taking a daily newspaper to help you keep track of time.
• Consider keeping a diary in which you can note down appointments, ‘to do’ lists and anything else you want to remember.
• Use sticky-backed notes to help remind you of things you have to do.
• Keep important things such as money, keys or spectacles in the same place, so you always
• know where to find them.
• Keep important phone numbers by the phone so they are always on hand.
• Arrange to pay regular bills by direct debit or standing order.
• Try not to be embarrassed if you forget something.
• If the right word or piece of information escapes you don’t try too hard. Once you stop trying it will often pop into your head.
• We all need help from time to time and other people are usually only too happy to be ]asked. Talk to family and friends about how they can help and support you.
• An occupational therapist may be able to help with devising strategies and using memory aids.

General health

• Take regular exercise.
• Stop smoking.
• Ensure adequate but not excessive sleep.

Referral criteria

There are no rigid criteria for referring patients for specialist assessment. Referral is appropriate when it is suspected that the memory loss is more than just minor, and/or the memory loss is suspected to be part of a wider picture of dementia which may require specialist intervention (e.g. pharmacological intervention).

NICE recommend taking the following into consideration when assessing a possible diagnosis of dementia in primary care:¹

• The individual’s self-report of changes in memory, capability or mood
• Informant histories that support self-report and add significant new details of changes
• Exclusion of depression and delirium as primary pathologies, using the information from the personal and informant histories
• Measurable cognitive losses, using a standardised instrument
• Absence of ‘red flag’ symptoms suggesting alternative diagnoses (for example, urinary incontinence or ataxia in apparent early dementia)

They also recommend considering referring patients who show signs of mild cognitive impairment, and an increased awareness of the risk of dementia in patients with learning disabilities, or a history of Parkinson's disease, stroke, or other neurological conditions.

The Memory Assessment Centre at Southampton have produced a useful referral guide, which outlines a protocol for diagnosing suspected dementia and excluding delirium and depression. It recommends referral for patients aged 65+ who have an ATMS of <8 and moderate to severe dementia, and for patients under 65 who have an ATMS of >8 and mild to moderate dementia.¹⁴

Of those with mild cognitive impairment, about 15% per annum will progress to dementia and 90% of this will be AD.¹⁵ Hence it seems fair to assume that mild but significant cognitive impairment probably represents the early stage of some form of dementia. If treatment for the condition is to be effective, it needs to be started at an early stage. Hence the need for early diagnosis.

Healthy living, with good control of cardiovascular risk factors, especially blood pressure is important. There is increasing evidence of the value of omega-3 fatty acids in prevention of dementia but no evidence from RCTs.¹⁸ Excessive alcohol consumption should be avoided. Higher education achievement also seems to give some protection but this may be related to people of higher education remaining mentally more active in retirement. The concept of use it or lose it is as pertinent to the mind as to the body.