Management of Parkinson's disease dementia and dementia with Lewy bodies
Ian McKeith and Murat Emre
Introduction
The management of the Lewy body dementias, namely Parkinson’s disease dementia (PD-D) and dementia with Lewy bodies (DLB), can be one of the most complex tasks facing neurologists, psychiatrists, geriatricians, primary-care physicians, or others caring for such patients [1]. On the one hand there is the risk of provoking severe neuroleptic sensitivity reactions, which can sometimes be fatal [2], on the other are the potentially gratifying beneficial effects of cholinesterase inhibitors (ChE-Is) [3]. Polypharmacy is the norm, with multiple treatment targets including motor impairment, cognitive deficits, sleep disorders, psychiatric symptoms, and autonomic dysfunction. Non-pharmacological treatments similarly need to be directed towards a variety of symptom complexes. Depending on the availability of resources it is apparent that the best delivery of care to a person with PD-D or DLB and his or her carers will be devised and reviewed by a multidisciplinary team of experienced specialists and delivered, when possible, in the patient’s home, minimizing the need for multiple hospital attendances. The general principles described in this chapter are applicable to most patients with a Lewy body-related dementia [4], the details of administration, dosing, and response varying more according to the individual person’s symptom mix rather than any particular diagnostic label (PD-D or DLB) which they might carry [5].
Making and disclosing the diagnosis
The clinical diagnostic approach and criteria have been described in Chapter 20. Although operationalized criteria [5, 6] can help clinicians to make confident and reliable diagnoses, common problems which remain in diagnosing PD-D are deciding whether cognitive impairment is severe enough to warrant a diagnosis of dementia [7] and the extent to which impairment of activities of daily living (ADL) is due to motor and autonomic symptoms alone. The distinction between PD-D and DLB also causes difficulties for some, but for the purposes of clinical management this may not be particularly important. The key is that the clinician is able to give a confident diagnostic label to the patient and family and follow this up with explanations for common questions, for example has the person with PD developed another disorder, such as Alzheimer’s disease (AD), to explain the dementia or whether the onset of confusion and hallucinations is due to side effects of medication or a consequence of disease progression. For lay people who do not have a grounding in neuroanatomy and physiology it can be difficult to understand how a single disorder can produce such widely variable symptoms as tremor, instability, constipation, hallucinations, sleep disturbance, and cognitive impairment. Time spent at this early stage in explaining the diagnosis and the mechanisms underlying symptoms, and checking out how well the patient and family understand what they have been told, is an essential part of forming the therapeutic alliance which will be required for the next stages of management. This is a particularly important step in developing non-pharmacological management strategies which need to address the manifestations of dementia in general plus the additional unique features of PD-D and DLB. The latter include fluctuating levels of cognitive and communicative ability, which are particularly perplexing and stressful for carers [8]. Useful materials to aid in this process can be found on a variety of websites produced by carer support organizations, statutory care providers, or specialist clinics, the latter often tailored to regional or local needs.
