Depression: Older people may present with the classical depressive symptoms seen in younger patients, but there are some special features in older age groups that may prevent its recognition:

• The elderly are less likely to admit to depressive symptoms spontaneously.
• The elderly depressed patient may present with persistent pain or other physical complaints
• Depression in old age may present with behavioural disturbance, especially in association with dementia.
• Apparent cognitive impairment or mental slowing, so-called “pseudodementia”, may be an indication of a primary depressive illness.
• In the setting of physical disability or illness, depression may be less easily recognised because of overlapping symptoms.

Dementia: People with dementia (loss of cognitive and intellectual ability caused by cerebral disease) frequently present to their primary care doctors with psychiatric symptoms. Common presentations in the doctor’s surgery that may indicate dementia are acute confusion (delirium superimposed on dementia), listlessness, inactivity and loss of interest (superimposed depression), and medical instability or injury (which may indicate poor compliance with treatment regimens). The cognitive impairment of dementia modifies the clinical presentation of other mental disorders so that it can be difficult to tease out specific target symptoms. For example, depression may be masked by cognitive slowing. It is wise to suspect depression in a patient with vascular dementia who becomes irritable or aggressive.

Forty per cent of people with dementia will develop psychotic symptoms during some phase of their illness

Dementia sufferers are more likely to develop delirium.

Delirium: The elderly, and particularly those with pre-existing dementia, are particularly vulnerable in the setting of acute physical illness and polypharmacy. Suspicions should be raised when there is a sudden onset or increase in confusion or when there is a fluctuation in a person’s mental state, especially when there is worsening at night.

Paranoid disorders: Schizophrenia and delusional disorders in old age can be longstanding or of recent onset. An annual incidence of about 17-23 per 100 000 has been reported in community surveys. Isolated elderly people may be psychotic for some time before they come to the attention of medical services. Initial referral may be via police or other community agencies. A typical presentation may involve an elderly person repeatedly asking police or doctor to intervene because they are being harassed in some way.

Anxiety: It is unusual for primary anxiety disorders to develop for the first time in old age. If they develop, general practitioners should be alert to the possibility of underlying depression or occult physical illness such as cardiac or thyroid disease. Like dementia and post-traumatic stress, longstanding but unrecognised anxiety may be revealed by the death of a spouse or the sudden discontinuation of prescribed or non-prescribed medication.