Illusions, in which, for example, a bedside locker is misperceived

as a threatening animal, commonly occur among people with

established impairment of vision or hearing. They are also found

in predisposed patients who are subjected to sensory deprivation,

notably after dark in a patient with clouding of consciousness.

They are suggestive of an organic illness such as delirium,

dementia or alcohol withdrawal.

True hallucinations arise without external stimuli. They usually

indicate severe mental illness, although they can occur naturally

16.9 Perceptions: definitions

Term Definition

Depersonalisation A subjective experience of feeling unreal

Derealisation A subjective experience that the surrounding

environment is unreal

Hallucination A false perception arising without a valid

stimulus from the external world

Illusion A false perception that is an understandable

misinterpretation of a real stimulus in the

external world

Pseudohallucination A false perception that is perceived as part

of one’s internal experience

324 • The patient with mental disorder

be neither overstated nor ignored. Any others at risk are most

likely to be family or, less commonly, specific individuals (such

as celebrities in cases of stalking) or members of specific groups

(defined by age, ethnicity, occupation and so on). Sometimes the

risk applies non-specifically to strangers, or to anyone preventing

the patient from achieving their goals.

There may be direct risk to life and limb (as in suicide, self-harm

or violence to others), or it may be an indirect risk, either to health

(through refusal of treatment for physical or mental illness) or

welfare (through inability to provide basic care – food, warmth,

shelter, hygiene – for oneself or one’s dependents). The risk may

be imminent, as in a patient actively attempting self-harm, or

remote, as in a patient refusing prophylactic medical treatment.

Direct risks tend to be imminent and indirect risks remote, although

this is not always so. A patient declining renal dialysis because

their depression makes them feel unworthy is at imminent but

indirect risk of death. Finally, the likelihood of the risk may range

from near certainty to hypothetical possibility.

A risk assessment should readily distinguish between cases

where there is an imminent, direct and near-certain risk to the

patient’s life (such as a man actively trying to throw himself from

the window to escape delusional persecutors), and those where

any risks apply to the welfare of other people, at some point

in the future, and amount to possibilities (such as a depressed

woman who may be neglecting her frail elderly father). The former

case calls for urgent intervention, probably via mental health

legislation; the latter requires engagement over time, preferably

in a voluntary way.

While all psychiatric evaluations require some assessment of

risk, it should be considered in depth whenever the presentation

includes acts or threats of self-harm or reports of command

hallucinations, the past history includes self-harm or violent

behaviour, the social circumstances show a recent, significant

loss, or the mental disorder is strongly associated with risk (as

in severe depression).

Assessing suicidality is the element of risk assessment that is

most often needed. If a patient presents after an act of self-harm

or overdose, the questions arise naturally (‘What did you want

to happen when you took the tablets? Did you expect to die?

Is that what you wanted? How do you feel about that now? Do

you still feel you’d be better off dead? Have you had thoughts

about doing anything else to harm yourself?’).

In other circumstances the subject will need to be introduced,

but do not fear that you may be putting ideas in the patient’s

mind (‘You’ve told me how bad you have been feeling. Have

you ever felt life is not worth living? Have you had any thoughts

about ending your life? How close have you come? What has

stopped you acting on those thoughts so far?’).

Capacity

Assessing capacity is a skill required of all doctors and should not

be delegated to psychiatrists. The legal elements vary between

jurisdictions but there are key clinical principles in common.

The first is the presumption of capacity: clinicians should treat

patients as retaining capacity until it is proven that they have lost

it. Secondly, capacity is decision-specific: patients may not be

able to understand the risks and benefits of complex medical

treatment options, while retaining the ability to decide whether

or not to enter a nursing home. Thirdly, residual capacity should

be maximised: if a patient’s ability to understand is impaired by

sensory deficits or language barriers, these should be corrected

new information; once this has registered, check retention

after 5 minutes, with a distracting task in between. Do the

same with the names of three objects; any error is

significant. Alternatively, use a six-item name and address

(in the format: Mr David Green, 25 Sharp Street, Durham).

More than one error indicates impairment.

• Long-term memory is assessed mainly from the personal

history. Gaps and mistakes are often obvious but some

patients may confabulate (that is, fill in the gaps with

plausible but unconsciously fabricated facts), so check the

account with a family member or other informant if

possible. Confabulation is a core feature of Korsakoff’s

syndrome, a complication of chronic alcoholism. Failing

long-term memory is characteristic of dementia, although

this store of knowledge can be remarkably intact in the

presence of severe impairment of other cognitive functions.

Impaired attention and concentration

These occur in many mental disorders and are not diagnostic.

Impaired attention is observed as increased distractibility, with

the patient responding inappropriately to intrusive internal events

(memories, obsessions, anxious ruminations) or to extraneous

stimuli, which may be either real (a noise outside the room) or

unreal (auditory hallucinations).

Concentration is the patient’s ability to persist with a mental

task. It is tested by using simple, repetitive sequences, such as

asking the patient to repeat the months of the year or days of

the week in reverse, or to do the ‘serial 7s’ test, in which 7 is

subtracted from 100, then from 93, then 86 and so on. Note

the finishing point, the number of errors and the time taken.

Intelligence

This is estimated clinically from a combination of the history

of educational attainment and occupations, and the evidence

provided at interview of vocabulary, general knowledge, abstract

thought, foresight and understanding. If in doubt as to whether

the patient has a learning disability, or if there is a discrepancy

between the history and presentation, a psychologist should

formally test IQ.

Insight

Insight is the degree to which a patient agrees that they are

ill. It can be broken down into the recognition that abnormal

mental experiences are in fact abnormal, agreement that these

abnormalities amount to a mental illness, and acceptance of the

need for treatment. Insight matters, since a lack of it often leads

to non-adherence, and sometimes to the need for compulsory

detention. You might ask ‘Do you think anything is wrong with

you’ or ‘If you are ill,