Abstract
ABSTRACT
An integrated care pathway (ICP) is proposed for the diagnosis of dementia syndromes, encompassing the various disciplines which may be involved (psychiatry, geriatrics, neurology, clinical genetics) due to the heterogeneity of presentation at the clinical and aetiological level. This proposed ICP challenges guidance recently issued by the National Institute for Health and Clinical Excellence (NICE) and the Social Care Institute for Excellence (SCIE), which requires a ‘single point of referral’ to access all dementia services. The proposal is prompted by the non-unitary nature of dementia, which may be envisaged as a ‘boundary’ condition transcending traditional professional categories and involving a wide array of professional groups in patient diagnosis in secondary care. Diversity rather than uniformity may best serve patient needs in such a heterogeneous syndrome.
INTRODUCTION
Dementia is a syndrome with many possible causes. 1,2 Although the age at onset is generally in later life, early-onset disease may occur. Most cases of dementia are of long duration, sometimes lasting for decades, with evolving symptomatology (neurological, psychiatric, functional) and hence changing care needs. All these factors suggest that developing a meaningful integrated care pathway (ICP) for dementia, which outlines key diagnostic and therapeutic tasks and their timing, 3,4 may be difficult, although attempts have been made. 5
All interested parties agree that early diagnosis of dementia is critical to appropriate implementation of any care pathway (of course there are potential penalties for incorrect early diagnosis, 6 although this is probably a rare occurrence). Dementia diagnosis has traditionally involved a number of clinicians. Although the diagnosis may be suspected in primary care, 7 general practitioners seldom undertake specific tests of cognitive function 8 and it is therefore specialists within secondary care who play the key diagnostic role. These may be physicians: geriatricians or neurologists; or psychiatrists: general or, more usually, old-age psychiatrists or psychogeriatricians.
Guidance on the identification, treatment and care of people with dementia was issued under the joint auspices of the National Institute for Health and Clinical Excellence (NICE) and the Social Care Institute for Excellence (SCIE) in November 2006. 9 This ‘guidance’ (adherence to which is required rather than optional) envisages that essentially all dementia care, from diagnosis to death, should be undertaken via a ‘single point of referral’, namely memory assessment clinics or community mental health teams, under the auspices of old-age psychiatrists. Many of these recommendations are stated to apply to all types of dementia. 9
While the potential advantages of these proposals from the perspective of continuity of care may be obvious, empirically it remains the case that psychiatrists often seek advice from neurologists concerning dementia diagnosis. Indeed, more than 20% of referrals in one dedicated neurology-led dementia clinic were from psychiatrists, 10 suggesting the possibility that psychiatrists value neurological input in diagnosis. This includes not only cases of primary neurodegenerative dementia (especially frontotemporal lobar degenerations [FTLDs] 10 ) but also primary psychiatric illnesses such as depression, anxiety and schizophrenia, deemed to have cognitive decline ‘out of proportion’ or ‘greater than expected’. Some neurological causes of dementia are not encompassed in the psychiatrists ‘Bible’, the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR), 11 such as FTLD with motor neuron disease (MND). 12
Since dementia is not a unitary diagnosis, and encompasses not only primary neurodegenerative disorders but also many other neurological conditions (so-called secondary dementias), with variable clinical features (age at onset, family history, symptomatology), aetiology, investigation, treatment and prognosis, 1,2 the argument for a ‘single point of referral’ seems perverse. Herein, an ICP for dementia is proposed that is inclusive of various diagnostic services, dependent on patient factors including age at onset and specific symptomatology.
PROPOSED INTEGRATED CARE PATHWAY FOR DEMENTIA DIAGNOSIS
All patients presenting with a complaint of memory loss or impairment in primary care require appropriate assessment, not summary dismissal, 13 although ‘storage failures’ and ‘action slips’ are not uncommon features of everyday, physiological, memory function. 14 An informant history to corroborate and/or elaborate the patient complaint is also essential, 15,16 since patients who attend alone seldom have dementia. 17 The specific presentation may determine whether referral to secondary care is required, and if so where is the most appropriate destination for assessment to be undertaken, although some overlap is inevitable (and not necessarily undesirable).
Referral to an old-age psychiatrist
For elderly individuals, the choice lies between old-age psychiatrists and geriatricians. For patients with monosymptomatic amnesia for recent events and new information causing repercussions in instrumental activities of daily living (IADL: private and public transport use, handling finances, medications; telephone use) and in whom the suspicion of Alzheimer's disease (AD) is therefore high, then a memory assessment clinic or community mental health team referral, as envisaged by NICE/SCIE, is entirely appropriate.
Likewise, for individuals with suspected primary psychiatric disorders which may impact on cognitive functions, such as depression, anxiety and schizophrenia, psychiatry or old-age psychiatry referral is indicated, dependent on age.
Referral to a geriatrician
Older individuals with a substantial burden of co-morbid illness (cardiac, respiratory, gastroenterological, endocrinological) which may impact on cognitive function 2 and which requires specialist management may be directed to a geriatrician, preferably one with an interest in dementia.
Referral to a neurologist
A number of features suggest that a neurology-led cognitive clinic, rather than an old-age psychiatry or geriatric clinic, is the most appropriate referral destination: specifically early age at onset, ‘atypical’ features, prominent neurological symptoms and signs, and possible genetic inheritance.
Early-onset dementia, arbitrarily defined as occurring before 65 years of age, encompasses a different case-mix compared with late-onset disease. 18 Although cases of AD, with onset in the 50s and 60s, still constitute the majority, the proportion of cases of FTLDs, such as frontotemporal dementia (FTD), progressive non-fluent aphasia and semantic dementia, increases. In addition to these primary neurodegenerative dementias, the frequency of secondary dementias also increases, 1 and likewise the spectrum of metabolic disorders. 19
AD itself is not a unitary condition; there are rare but well-described variants (‘atypical AD’), including:
posterior cortical atrophy or biparietal AD, presenting with visual agnosic complaints (orientation, recognition); a slowly progressive aphasia; a slowly progressive apraxia; a frontal variant with early marked behavioural features, akin to frontal variant FTD.
The frequency of these variants is uncertain, but may approach 10%. 20,21 These ‘atypical’ presentations have a differential diagnosis (e.g. prion disease, FTD, corticobasal degeneration) and ideally require evaluation in neurology-led clinics.
Although additional neurological symptoms and signs may sometimes be present in AD, such as myoclonus, epileptic seizures and parkinsonism, their presence should alert clinicians to the possibility of other diagnoses in the spectrum of secondary dementias, particularly if they occur early in the disease course. These neurological signs include:
parkinsonism (which may suggest Parkinsons's disease dementia, dementia with Lewy bodies, progressive supranuclear palsy, corticobasal degeneration, ‘normal pressure hydrocephalus’); myoclonus (prion disease); ataxia (multiple sclerosis, prion disease); sensory complaints (multiple sclerosis; prion disease); muscle wasting and fasciculation (FTLD/MND); chorea (Huntington's disease, although this more usually presents as a movement disorder and hence to general neurology rather than cognitive clinics
22
); apraxia (corticobasal degeneration); spastic paraparesis (multiple sclerosis).
There can be little doubt that patients with such neurological signs are best evaluated in a neurology-led clinic.
Though uncommon overall, some dementias result from deterministic genetic mutations inherited as monogenic Mendelian disorders; their frequency is greater in cohorts with early-onset dementia. Deterministic mutations for AD have been identified in three genes, encoding amyloid precursor protein, presenilin-1 and presenilin-2, of which presenilin-1 mutations are the most common. 23 Other examples of genetic dementias include Huntington's disease (tri-nucleotide repeat expansion in IT15 gene), familial FTDs (tau or progranulin mutations), familial prion diseases (prion protein gene mutations) and CADASIL (Notch3 mutations [cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy]). 2 Some neurological dementia clinics have built up considerable expertise in addressing the genetic aspects of dementia, but this is an area in which the assistance of clinical geneticists may be required, especially for genetic counselling prior to neurogenetic testing.
Referral to a clinical geneticist
Although diagnostic genetic testing in individuals with appropriate clinical phenotypes may be undertaken in neurology-led clinics, predictive testing remains the province of clinical geneticists because of the need for detailed genetic counselling prior to test. Asymptomatic family members of patients diagnosed with, or suspected to have, a genetically determined dementia should be referred to a clinical geneticist, as is already the case for Huntington's disease. NICE/SCIE recognizes that such patients and their unaffected relatives should be offered referral for genetic counselling. 9
Increasingly in the future, dementia syndromes will be diagnosed on the basis of biomarkers, as well as clinical history, without the necessary clinical correlate of dementia. 24 Since neurogenetic tests feature among these biomarkers, clinical geneticists may be required to adopt an increasingly important role in the diagnostic dementia care pathway.
CONCLUSION
A diagnosis of dementia has profound consequences (social, psychological, emotional, financial) for individuals, their families and carers, and it therefore behoves clinicians to ensure correct diagnosis, including establishing the aetiology of dementia, in order to ensure that appropriate treatment and prognosis may be given. The multiple causes of dementia necessitate careful diagnostic assessment.
Dementia is neither a neurological nor a psychiatric disease: it is a brain disease that may be attended by either neurological or psychiatric features or both, and hence it does not respect traditional professional boundaries. Therefore, there can be no argument that it should be managed solely by neurologists or psychiatrists, disciplines with a shared basis in neuroscience. Nor is dementia a unitary, or uniform, condition, as seems to be the implication of the NICE/SCIE guidance. Therefore, a truly integrated care pathway must acknowledge the input from both these disciplines, and possibly others (neuroradiology, neuropsychology, neurosurgery, geriatric medicine, clinical genetics, occupational therapy, speech and language therapy), variable with patient factors such as clinical presentation, specific diagnosis and stage of disease. There emphatically remains a place for physicians, both geriatricians and neurologists, in the diagnostic phase of dementia, pace NICE/SCIE, since the diagnostic process requires clinical skills generic to these specialties.
If it is possible and desirable to integrate across the health/social-care divide, one of the laudable goals of the NICE/SCIE guidance, then it should be possible to integrate care over different clinical specialties. Although NICE/SCIE guidance claims to be evidence-based, it is susceptible to this challenge: to provide any evidence base to support a ‘single point of referral’. Clinical experience suggests that far from narrowing the referral base, this will need to broaden as new diagnostic modalities become increasingly available. To borrow a concept from neuropsychology, the NICE/SCIE guidance seems stimulus-bound, being drawn to one salient aspect of dementia rather than integrating all its components.