One key aspect of the cognitive history is the necessity of gaining a witness or corroborative account. By their nature, cognitive impairments may include lack of insight and impaired ability to express details of the history as a result of memory, language or other cognitive deficits. It is therefore strongly recommended that a witness history is taken and it is often beneficial to perform this separately from the patient, particularly if personality or behavioural changes are to be exposed.

An in-depth discussion of all aspects of the cognitive history is beyond the scope of this chapter and we have excluded the well-known aspects of past psychiatric history, past medial history, educational and occupational history and social and family history in favour of highlighting some tips specific to cognitive history taking, which although not meant to be foolproof, nevertheless may provide helpful clues to direct the clinician.

Initial Presentation and Impressions

Although not without exception, on the whole, if a spouse, friend or carer is the instigator of the referral, this is more suspicious of an underlying organic brain disorder than patients who self-present. Patients who attend a clinic alone have a much greater chance of having an underlying affective cause of their symptoms than those who are accompanied.

Many patients who are ‘brought’ to a consultation adopt this role very quickly and defer to their spouse or friend in sitting down and answering questions. A common occurrence is the response to the first greeting or question – when the examiner asks why the patient has come to see them, the patient may immediately turn to their spouse for help or confirmation without actually addressing the question. Anecdotally this reaction seems to have a fairly high specificity for underlying organic brain disease.

Presenting Complaint

It is important to clarify the first symptom that has been noticed by the patient or carer. Patients presenting with moderate stages of dementia may have a multitude of symptoms that overlap between dementia subtypes and often the first symptom can be instructive regarding diagnosis. For example, memory deficits are invariably the earliest feature of Alzheimer’s disease whereas behavioural changes are invariably the initial feature of frontotemporal dementia despite both sets of symptoms being present in both conditions as they progress.

It is often difficult for patients or informants to be accurate about the duration of symptoms which are usually underestimated. A little gentle probing can often extend the history from an initial estimate of six months to several years, thereby narrowing the differential diagnosis. It is useful to ask such questions as ‘how were they three years ago – were they the same as 20 years ago?’

Behavioural and Personality Changes

To get a clear history of behavioural or personality change, the interviewing of an informant is critical as lack of insight often accompanies such behavioural changes. Major personality change is usually a result of pathology in the limbic, paralimbic and frontal-striatal systems. They may be seen in space occupying lesions of the frontal lobe and subcortical dementias but the condition where specific personality changes are virtually diagnostic is frontotemporal dementia.

A simple question such as ‘have you noticed any changes in X’s behaviour or personality?’ is usually a helpful opening gambit. A not uncommon response in frontotemporal dementia is that ‘they are not the same person that I married’.

Behaviours to probe for include apathy, passivity and lack of initiation. Indeed some patients are often content to let others discuss less than complimentary changes in their behaviour or personality without need to interject or justify themselves in any way. Disinhibited behaviour can be enquired about in terms of whether the patient has done or said anything that causes embarrassment or is inappropriate, especially in public. Rigidity in behaviour may be evidenced by strict and unnecessary time keeping or eating habits such as always eating the same food at the same time of day. Obsessive and compulsive behaviour should be questioned and the duration of this ascertained to differentiate from longstanding personality traits. Gradual loss of empathy and blunting of emotional repertoires should be sought and a change in food preferences for sweet things or the development of a catchphrase are both behavioural changes that are virtually pathog-nomonic of frontotemporal dementia.

Autobiographical History

It is useful to go through details of schooling and major life events in early adulthood, primarily to see if the subject has impaired autobiographical memory. An inability to remember where they went to school, when they were married and where, or what their first job was, is concerning for an organic dementia as these memory abilities are not usually affected in psychiatric disorders.

Medications

Elderly populations may have a multitude of medical and psychiatric co-morbidities and hence multiple medications, many of which may affect cognition. Particular medications to note are opiate-based analgesics such as codeine or tramadol, medications with anticholinergic properties such as tricyclic antidepressants, antispasmodics, anti-emetics, anti-parkinsonian medication, bronchodilators, or antiarrhythmics.

Activities of Daily Living

Ask about performance at work if appropriate, ability to travel to new locations alone, handling of finances and bank accounts, social events, use of household devices including telephones, TVs etc., preparation of meals, organizing of family events such as trips and holidays. A gradual change of responsibilities from patient to spouse or other carer over several years is revealing.

The bedside cognitive assessment starts with observation of the patient. Watch how the patient enters into the consultation room, paying particular attention to their gait and observe how they sit down in a chair.

The gait abnormality of idiopathic Parkinson’s disease is easy to recognize if one is watching for it. Slow and shuffling with short steps, narrow base, stooped posture with decreased arm swing. It is surprising how often this is overlooked. If a diagnosis can be made before the patient has sat down, it is very helpful for the rest of the consultation! The gait of cerebrovascular disease is characterized by the sense that the feet are rooted to the ground with a more wide-based gait, again with small steps. The gait of normal pressure hydrocephalus is usually more wide-based than that of cerebrovascular disease and is unsteady with less adherence of the feet to the floor.

Further useful information can be taken from watching the patient sit in a chair – difficulty in orienting to the chair or sitting on the edge or armrest of a chair by mistake suggests significant apraxia. If a patient falls back heavily into a chair, be on the lookout for additional signs of progressive supranuclear palsy.

Throughout a cognitive assessment it is useful to keep the question in mind of whether one is dealing with a predominantly cortical or subcortical picture of impairment. The cardinal features of a subcortical cognitive impairment are slowing of thought, response and movement with impaired attention. The major cortical deficits to look out for are language impairment (aphasia), visuospatial impairment and praxis and so the finding of one of these deficits suggests cortical involvement (note the rare exceptions of aphasia from basal ganglia lesions). Memory deficits may be present in both cortical and subcortical syndromes.

Another important question to return to during the consultation is whether the patient has an organic or psychiatric origin to their symptoms. Although it is not always possible to be certain, there are certain clues from both the history and examination that may guide the examiner. Symptoms that are fluctuating or specific to either the home or workplace are suspicious for psychiatric symptoms, as are symptoms that are noticed solely by the patient rather than others. In the examination, psychiatric syndromes may often manifest with impaired memory, executive functions and processing speed deficits but the presence of real language deficits, apraxia or visuospatial function is far more concerning for organic brain disease.

Cognitive Rating Scales

The most widely used screening tool for bedside cognitive assessment is the Mini Mental State Examination (MMSE) which typically takes 8-10 minutes to administer and assesses orientation, memory, language and visuospatial function and is scored out of 30 points. As the MMSE is the subject of a separate chapter (see Chapter 27), it will not be described in detail here, but it is worth considering a few of its major advantages and disadvantages. Advantages:

• ease of administration;
  
• wide use helps comparison of scores across patients and testing centres;
  
• suitable for longitudinal assessment;
  
• quick.

Disadvantages

• does not assess speed of information processing or executive function;
  
• minimal assessment of memory;
  
• ceiling effect in mild cognitive impairment and frontotemporal dementia;
  
• test-retest reliability (intra-rater) of +/- 3;
  
• inter-rater reliability suspect on serial 7s and ‘world’ backwards.