Depression is common among the elderly, but often goes undiagnosed states Professor Mohan. GPs frequently attribute their symptoms to co-existing physical condition or dementia. Treatment is just as effective in the elderly as in younger patients but newer treatments such as SNRIs and SSRIs are preferred to tricyclic antidepressants as they are less toxic in overdoses and have fewer anticholinergic side effects.

Depression in the elderly is relatively common and is seen in approximately 10Ð15 per cent of those who live in the community. The prevalence rises in those attending their general practitioners (GPs) (15Ð30 per cent), those who live in care homes (30Ð40 per cent), and those who are hospitalized (15Ð50 per cent)1. Depression in later life often coexists with other illnesses and disabilities and may be triggered by the death of a spouse, retirement, and/or relocation. Many elderly people may deny that they are depressed due to a perceived stigma associated with a psychiatric condition or they may simply not recognize their symptoms as signs of depression.

All these factors make detecting depression in the elderly difficult, so that effective treatment is often delayed. Failure to treat depression leads to increased morbidity and mortality and increases the demands made on health, social services, families, and carers. Antidepressant treatments are safe and effective and most elderly patients will respond well to appropriate medication.

Diagnosis
As recognizing depression in the elderly can be difficult, it is helpful if GPs bear the condition in mind when dealing with their elderly patients. Proactive questions may be needed to establish whether symptoms such as fatigue, insomnia, and poor appetite (Table 1) are due to physical illness or to depression. Nervousness, irritability, and anxiety are also common features of depression in older patients and are found in around 80 per cent of those diagnosed.

Many older people will not admit to feeling depressed for fear of seeming weak or ÔmadÕ. Yet symptoms such as a loss of interest in friends, family, or socializing, feelings of guilt or marked pessimism, and suicidal thoughts experienced over several weeks are all suggestive of major depression. The reluctance of the elderly to recognize their depression may account for the fact that they are less likely than younger patients to complain of low mood. They are, however, more likely to ÔsomatizeÕ their depression, complaining of increased aches and pains. This tendency to experience and communicate somatic symptoms unaccounted for by relevant pathological findings can often lead to unnecessary investigations and treatment2. It is worthwhile asking patients if they have experienced recent significant life changes as the loss of a spouse or close friend, or retirement can affect their mood. The presence of chronic pain and illness, difficulty with mobility, or frustration caused by memory loss are also likely to increase the risk of depression.

Spotting the differences between dementia and depression
While cognitive deficits are frequently seen in older people it is important to try to differentiate between symptoms of depression and dementia which are often mistaken for each other. There are, however, some important differences between depression and the early stages of dementia. First, and most obvious, is that in people with dementia the reasoning ability of the individual is obviously impaired, while the depressed individualÕs reasoning is preserved. Second, the depressed individual is more likely to show good orientation to time, place, and space while the demented person shows impairment. Third, the demented individual usually tries to cover up any memory impairment, while the depressed individual constantly complains about an inability to remember3. In addition, the memory of a depressed patient often improves with cues, whereas a patient with dementia will not remember regardless of the number of cues given.

Although these distinctions between dementia and depression appear to be fairly clear cut and depression is much more common than dementia, diagnosis is further complicated by the fact that depression may be the presenting feature of a dementia, particularly of AlzheimerÕs disease. When this is the case, symptoms may vary from mild depression to severe emotional liability.

Screening scales
A number of Ôscreening scalesÕ have been developed, which can help identify elderly patients who need more detailed interview and appropriate treatment. The Geriatric Depression Scale (GDS)4, recommended by the Royal College of Physicians, British Geriatrics Society, and the Royal College of General Practitioners, is a self-rating scale that can also be given by interview. It is easy to administer and has been well validated in many environments. The original GDS was a 30-item questionnaire that was time-consuming for both staff and patients, but a later version cuts down the questions to 15 with the first four questions (Table 2) designed to screen out those who are not depressed.

Another screening scale which can be used in physically ill people and which requires no specialist psychiatric knowledge is the Evans Liverpool Depression Rating Scale (ELDRS)5. This is particularly useful, as it asks about suicidal thoughts. Risk from suicide is known to increase with age and physical disability, and in the elderly, death can also occur as a result of non-compliance with medication4.

Treatment
Most antidepressants are believed to be as effective in the elderly as they are in younger people7, although a number of factors should be carefully considered before prescribing. Antidepressants usually take 1Ð4 weeks before their effect is evident, but this delay may be longer in elderly people. If patients do not respond, compliance should be checked and the diagnosis reconsidered before changing or adding drugs. Many elderly patients will already be taking a number of other drugs, so where possible choose drugs such as venlafaxine, sertraline or escitalopram, which minimize drug interactions. After the initial treatment response, the drug should be continued at the same dose for at least 4Ð6 months, although some elderly patients may need to continue their treatment for longer. The dose should be gradually lowered over several weeks before withdrawal8.

Selective serotonin reuptake inhibitors (SSRIs) such as sertraline and escitalopram or serotonin and noradrenaline reuptake inhibitors (SNRIs) such as venlafaxine are recommended as first-line treatment for moderate to severe depression because they are relatively low in toxicity9 in overdose and are better tolerated than tricyclic antidepressants (TCAs)10. There is also evidence to suggest that SNRIs, such as venlafaxine, are more effective than SSRIs and TCAs in treating somatic symptoms of depression, which, as we have seen, is a particular trait of depression in the elderly11.

Elderly people are generally more susceptible to anticholinergic effects, and antidepressant treatment with tricyclics can precipitate acute confusion because of the centrally acting anticholinergic side-effects12. If a tricyclic antidepressant has to be used, drugs with pronounced anticholinergic effects should be avoided, and the dose should be kept lower than in younger subjects. Monoamine oxidase inhibitors (MAOIs) should never be combined with either SSRIs or SNRIs and only used very cautiously with TCAs. An SSRI or related antidepressant should not be started until 2 weeks after stopping a MAOI. Conversely a MAOI should not be started until at least a week after an SSRI or related antidepressant has been stopped (2 weeks in the case of paroxetine and setraline, at least 5 weeks in the case of fluoxetine)13. Elimination of all signs and symptoms of depression (remission) should be the key goal for treatment, as it has been shown that patients who have residual symptoms of depression after stopping treatment are more likely to relapse14.

Counselling or psychotherapy may be appropriate for some older people, especially those who have very little or no social support systems. They can also be an opportunity for advice about how to improve self-care and nutrition. However, such sessions are not appropriate to all.

Conclusions
Depression in older people is prevalent, particularly in those in care homes and hospitals, and can be hard to recognize. Screening scales can be useful in identifying depressed patients. However, the social stigma associated with mental illness is particularly strongly felt by elderly patients brought up to keep their personal problems to themselves and to display a Ôstiff upper lip.Õ For those who will accept such help, antidepressant treatment along with counselling can be very effective.

References
Frm Editorial office Professor Mohan is Associate Medical Director and Consultant and Programme Advisor in Old Age Psychiatry, North Birmingham Mental Health Trust, Birmingham

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