Clinical Assessment and Differential Diagnosis David N. Anderson

DIFFERENTIAL DIAGNOSIS

The point prevalence of paranoid ideas in the general elderly pop-ulation is 4–6%^6–8. A population-based study from Sweden found 8% of non-demented 70-year olds developed first-onset psychotic symptoms during a 20-year follow-up and of those surviving to age 85 the cumulative incidence was 20%⁹. These were most commonly visual hallucinations and persecutory delusions. The more common conditions will be reviewed briefly from the perspective of clinical differentiation, although for detailed consideration reference should be made to the relevant chapters.

Delirium (Acute Confusion)

The history is short, usually days or a few weeks, and the onset rapid. A structured assessment, using validated instruments, of 100 people with delirium (17% also had dementia) found 50% experienced per-ceptual disturbances and hallucinations and 31% delusions¹⁰.These are typically poorly organized, fluctuating and variable in content, while hallucinations most commonly occur in the visual modality and can be vivid and complex. Other features of delirium will normally be present.

Alcohol intoxication and withdrawal from alcohol, benzodi-azepines and barbiturates may all cause paranoid delirium, and withdrawal syndromes should be particularly considered when psychosis develops shortly after a hospital admission.

Dementia (Chronic Confusion)

Ballinger etal.¹¹ found delusions and hallucinations in 38% and 34%, respectively, of 100 dementia admissions. Another study of 178 Alzheimer’s patients revealed persecutory ideation (20%), delu-sions (16%) and hallucinations (17%) to be common¹². Fifty per cent of patients with multi-infarct dementia may have delusions at some time¹³. Paulsen etal.¹⁴ reported a cumulative incidence for hallucinations and delusions of 51% over four years for people with probable Alzheimer’s disease. The clinical course of diffuse Lewy body disease is particularly characterized by psychotic symptoms, and visual hallucination is a defining characaterisic¹⁵. In this case the hallucinations may precede other evidence of the disorder.

The manifestations of progressive, global, cognitive impairment will usually be present, although dementia may present with paranoid symptoms that can be indistinguishable from functional illness¹⁶. Paranoid ideas are frequently related to cognitive deficits, especially memory, leading to accusations of theft or problems arising from perceptual difficulties and misidentification¹². Like delirium, these fluctuate and may be ferociously denied, or forgotten, at interview, although the theme and content remain fairly consistent.

Depression

If depression is of delusional proportions, biological and character-istic depressive symptoms are usually marked. Delusions and hallu-cinations, occurring in all sensory modalities, are normally mood-congruent but incongruent symptoms occur and may be difficult to distinguish from those of primary paranoid disorders.

Kay etal.¹⁷ suggested six historical variables that help distinguish affective and paranoid psychoses: life events and family history of affective illness favoured an affective diagnosis, while low social class, few surviving children and social deafness favoured paranoid disorder. Premorbid personality proved the best discriminator, with paranoid patients being solitary, shy, touchy, suspicious and emotion-ally aloof, and patients with affective disorders reporting subjective ratings of high premorbid anxiety.

Mania

Traditional teaching suggested that mania in old age was both rare and atypical in presentation. Broadhead and Jacoby’s¹⁸ prospective study found that young and older-onset patients were clinically very similar. The onset of mania in old age is more common than once thought¹⁹ and the majority of patients will have a history of affective disorder, some 50% having had three or more depressive episodes, with a latency of 15–17 years from first depression to mania^18–21 .

Organic Delusional/Hallucinatory Disorder

Paranoid hallucinatory disorders have been associated with a variety of organic conditions^3,8,2225 and pharmacological agents^3,26,27.The symptoms may be typical of functional disorders²⁸ and the diagno-sis depends on establishing a clear aetiological link and temporal relationships between a physical disorder or drug and mental distur-bance. As Kay put it, ‘Had the organic diagnosis not been reached independently of the psychiatric symptomatology, most of the cases would have been regarded as, indubitably, schizophrenic’²⁸.

The more common causes encountered in clinical practice include hypothyroidism, intra-and extracerebral tumours, epilepsy and cere-brovascular disease, and pharmacological agents such as psychostim-ulants, anti-parkinsonian and dopaminergic drugs, and steroids.

Possibly the most common is the psychosis of Parkinson’s disease. This may be seen in the presence or absence of dementia complicat-ing Parkinson’s disease, and psychotic symptoms may occur at any stage. Up to 50% of people may develop psychotic symptoms and 30% experience visual hallucinations within the first five years^29,30. Visual hallucinations are most common though auditory hallucination and delusions can occur.

Paranoid Personality Disorder

This is necessarily a life-long problem, which must be demonstrable from early adulthood. It is characterized by a sensitive and defensive attitude that causes people to feel they are victims of life and inter-pret events in a self-referential way. The effects of ageing and the vicissitudes of later life may accentuate these traits and, if dementia or functional illness supervenes, will colour the symptomatology.

Late-onset Schizophrenia

The development of ICD-10³¹ and DSM-IV³² saw the disappearance of age-defined categories of schizophrenia. This reflects the evidence that the symptoms are essentially the same regardless of age, cer-tainly positive symptoms. It is estimated that 23.5% develops after age 40³³, and first admission data suggests the annual incidence of schizophrenia-like psychosis increases by 11% for every five-year period for people over the age of 60³⁴.

Though positive symptoms are similar regardless of age, negative symptoms are much less common with onset after age 60, when visual hallucination may be more common².

Familial risk and genetic contributions to aetiology decline with increasing age of onset. With onset over age 60, the association is weak but associations with sensory impairment, particularly deafness, and social isolation are more evident. These differences led an inter-national consensus to recommend the nomenclature of late onset to refer to onset after age 40 and very late onset after age 60². The pre-ponderance of females in the very-late-onset group appears to be con-sistent, and very-late-onset cases seem more likely to have premorbid paranoid or schizoid traits though not amounting to personality dis-order. Later onset is typically associated with better premobid educa-tional, occupational and psychosocial functioning than early onset².

However, prevalence and gender ratio have been shown to vary in a study of first contacts with onset after age 60 in migrant populations in London^35,36.

Roth and Kay³⁷ provide a thoughtful discussion of the apparent similarities and differences of the associated features of late-and early-onset schizophrenia.

Delusional Disorders

These are conditions characterized by a persistent, circumscribed delusional theme, and if hallucinations occur they are not prominent.

They are defined by their delusional content, which may be erotic, jealous, hypochondriacal, persecutory or grandiose. These conditions have not been the subject of systematic study in old age, when they are thought to be relatively rare²⁶. Onset is usually in middle age but as patients normally function well outside their particular delusion and symptoms frequently persist, they may present in old age. Unlike late-onset schizophrenia, delusional disorder seems not to be asso-ciated with premorbid paranoid personality or deafness³⁸, although querulent paranoia has been related to deviant personality structure³⁹.

Familially they appear unrelated to affective or schizophrenic illnesses^40,41.Howard etal.⁴² found dilatation of lateral and third ventricle volumes by magnetic resonance imaging (MRI) to be more a feature of delusional disorder than schizophrenia in old age, as defined by ICD-10 criteria.

A small retrospective study comparing paraphrenia (schizophrenia of late onset) with paranoia (delusional disorder of late onset) found cerebral infarction on CT brain scan to be a feature of paranoia rather than paraphrenia. Furthermore, social isolation and being unmarried were not features of paranoiacs with cerebral infarction, suggesting separate groups defined by organic or social associations. Response to antipsychotic drugs was worse for paranoia⁴³.

ASSESSMENT

Interview

Interviewing paranoid elderly people may be complicated by deaf-ness, speech problems or visual handicap, so time and patience are essential. An informant history is mandatory and often several sources may be required.

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