Clinical features
Other than more frequent somatic and hypochondriacal complaints, patients with depression in later life are little different, symptomatically, to younger adults.
(1) An exception may be the recently described ‘vascular depression’ (depression linked to small vessel disease of the brain), in which depressive ideation is less but cognitive impairment and apathy greater. In most cases then the pathoplastic effects of ageing and ill-health are what mainly influence the presentation of depression in later life (
Table 8.5.4.1).
An overlap of symptoms due to associated physical ill-health may lead to diagnostic difficulty, and determining whether a symptom has arisen predominantly because of affective disorder or a medical condition can be difficult for those without the necessary experience.
Older depressed patients may
minimize feelings of sadness and instead become
hypochondriacal (morbidly preoccupied with a fear of illness).
(1) Late-onset
neurotic symptoms (
severe anxiety,
phobias,
obsessional compulsive phenomena or hysteria) are usually secondary to depressive illness. Any act of
deliberate self-harm suggests depression, as elderly people rarely take ‘manipulative’ overdoses. An overdose in an older person should never be dismissed because its effects, in purely medical terms, were trivial.
All require psychiatric assessment. Severe depression may mimic dementia.
Table 8.5.4.2 highlights the main differences between progressive dementia and the pseudodementia of depression. Pseudodementia is a term which is perhaps waning in use as it has become clear that depressive disorder is commonly associated with cognitive impairment, which may not be reversible, even with adequate treatment of depression. Pseudodementia is often applied to an older depressed patient who, on presentation, appears very confused, with frequent ‘don’t know’ responses. However, the onset of confusion is acute, easily dated, the patients convey their despair non-verbally, and, unlike the person with degenerative dementia, complain vociferously about their memory. Cortical signs (aphasia, apraxia, etc.) suggest a primary dementia with a super-added depression rather than depressive pseudodementia. Wandering off and getting lost suggests dementia but occasional cases are seen of fugue states caused by severe depression mimicking disorganized behaviour in dementia. The key is a good history.
An unusual behavioural disturbance may occasionally be a leading symptom of depression. Examples include the onset of incontinence in an older person who feels trapped in a situation of resented dependency in a residential or nursing home, late-onset alcohol abuse or, rarely, shoplifting.
(a) Vascular depression
In vascular depression, vascular disease is judged to predispose, precipitate, or perpetuate depressive symptoms. Evidence (summarized by Baldwin
(2)) includes the following. There is a high rate of structural brain abnormalities in both white matter and basal ganglia grey matter on imaging and on post-mortem examination of older patients with depressive disorder, notably with a late age of onset. Psychomotor change, apathy, and executive dysfunction (leading to slowed responses, failure of initiation, impersistence in tasks, and inefficient memory) occur characteristically in such patients. Strategic lesion location, sufficient to disrupt subcorticalfrontal circuitry, is associated with poorer depression outcomes, and progression of such lesions is associated with later incident cases of depression in those not already depressed. The concept of vascular depression is discussed critically under aetiololgy.
Diagnosis and differential diagnosis
(a) Assessment
The psychiatric history should include a collateral history as well as drug evaluation (prescribed, ‘borrowed’, and over-the-counter) and alcohol intake. A cognitive screening test should always be undertaken. A physical evaluation should focus on possible disorders causing an organic mood disorder (
Table 8.5.4.3), including medication. Non-selective β-blockers, calcium antagonists, benzodiazepines, and systemic corticosteroids were the main culprits in one study.
(3)Screening questionnaires can be used to help diagnose depression, especially in settings such as medical wards where the prevalence is high, but their results must be informed by clinical judgement. The Geriatric Depression Scale (GDS) (Geriatric Depression Scale website http://stanford.edu/˜yesavage/GDS.html) is widely used. It focuses on the cognitive aspects of depressive illness rather than physical depressive symptomatology, and has a simple ‘yes/no’ format (
Table 8.5.4.4). It loses specificity in severe dementia but performs reasonably well in mild to moderate dementia. For rapid screening four questions (1, 3, 8 and 9) can be used.
(b) Investigations
Table 8.5.4.5 summarizes investigations appropriate for a first episode of depression and a recurrence. A guiding principle is that elderly people are in a more precarious state of homeostasis with their environment because they have less physiological reserve.
Severe depression in a 75-year-old may lead to quite serious metabolic derangement which would be unlikely in a fit 35-year-old.
An electroencephalogram (EEG) can help in differentiating depression from an organic brain syndrome such as delirium or an early dementia. A brain scan is only performed if clinically indicated, for example a rapid-onset depression with neurological symptoms or signs. The Dexamethasone Suppression Test (DST) is less specific for depressive illness than was first thought. It cannot reliably differentiate dementia from depression.
(c) Differential diagnosis
Organic mood disorder is diagnosed when a direct aetiological link can be established between the onset of the mood disorder and an underlying systemic or cerebral disorder (including dementia), or an ingested substance such as medication or alcohol.
Bipolar disorder is covered later. Psychotic illness (schizophrenia or delusional disorder) may present with marked depressed affect but other symptoms are present. A common depressive delusion in old age is hypochondriasis and sometimes it is difficult to decide whether the patient has a psychotic or an affective disorder. Interpretation depends on which symptoms predominate; if they occur together, it may be appropriate to use the term schizoaffective disorder.
Dysthymia chiefly occurs in younger adults but may occur in later life in association with chronic ill-health. Where there is a clear onset of depressive symptoms within 1 month of a stressful life event without the criteria for a depressive episode being met, then an adjustment disorder may be diagnosed.
