Differential diagnosis and treatment – a whistle stop tour of Lewy body dementia

Lewy body dementia (LBD) and Parkinson’s disease dementia (PDD) together account for up to 15% of all dementias. Recognition and management of these dementias, though, is often suboptimal, and people living with them can fall through the gaps in care.

A brand new Academy has been established to try to help close that gap, and on 25th June, our first webinar in dementia with Lewy bodies took place. Dr Tim Rittman, consultant neurologist at Addenbrookes and senior clinical research fellow at University of Cambridge, and Alison Wilkinson, Dementia nurse consultant at Peterborough NHS Foundation Trust, spoke to 183 live attendees on the treatment and management of Parkinson's dementia (PDD) and Lewy body dementia (LBD) - and the session is available on demand now.

Looking for LBD: when it is, and when it isn't

Tim began the session by noting that dementia with Lewy bodies comes with complex motor and cognitive impact and that it is both over and under diagnosed. He then gave a helpful list of all the times that clinicians may be inclined to assume LBD, when it might not be present, including:

• Parkinson's dementia

• Vascular dementia when it causes hallucinations or sleep disorders

• Hallucinations in Parkinson's

• REM sleep behaviour disorder

He cited McKeith (1996)'s guidelines for LBD diagnosis and outlined hallucinations as being characteristic when they are (usually) involving people who are still and silent, and not usually frightening. Sharing that they often begin as misperceptions (seeing one thing but thinking it is another) and pointed towards Rollins (2019) work on how the type of hallucination can indicate the underlying condition. (For example, hallucinations of animals are less indicative of LBD).

Other key observations to help diagnose LBD; those living with LBD:

• will typically experience massive fluctuations in ability from day to day

• may have mild Parkinsonism but it will usually be upper limb rather than lower limb (which is more common in vascular dementia), and it might look like bradykinesia but it will have a decrement to it.

have a distinct cognitive profile in LBD - for example, in the Addenbrooke's Cognitive Assessment,someone with Alzheimer's might remember the information to begin but forget later, whereas with LBD they may find it difficult to recall all 7 objects at the start - but the ones they do remember, they will still recall at the end of the discussion.

Table 1: Helpful comparison of cognitive profile between Alzheimer's and dementia with Lewy bodies

Key biomarker considerations in diagnosing LBD include:

• MRI scans are often normal.

• DAT scan can be useful in distinguishing between AD and LBD to understand if it is a Parkinsonian dementia or not?

• FDG PET scan can be helpful if the cingulate is present

• Polysomnography can be useful to check for REM behaviour disorder

• Cardiac MIBG scan could be used to detect sympathetic nerve damage associated with LBD

Tim encouraged professionals to consider differential diagnoses when diagnosing LBD and to look for its clear cognitive profile, using biomarkers to help rule out or hone down where needed. In closing, he referred to the following key reminders:

• Look for subtle executive change - people may be able to take in lots of information but not to organise it well or refer to it in the conversation

• Posterior visuospatial and impaired speech fluency is more prevalent early on in LBD

• It might start out looking like 'Grumpy old man syndrome'

• A common differential diagnosis is Multiple system atrophy (MSA) where both cognitive impairment and erectile dysfunction are less common.

Practical Management of LBD

Following Tim's talk, Alison Wilkinson, dementia nurse consultant, discussed the challenge of supporting the 'whole person' with LBD, noting that often, there can be an array of healthcare professionals all 'trying to look after their own bit of person'. She was clear that it is essential that everyone works collaboratively to a shared and clear treatment pathway, and gave a very practical overview of optimal management, both pharmacological and behavioural or lifestyle-related.

Cognition

Noting that most medications given to support cognitive stability are cholinesterase inhibitors (including domeprazil, rivastigmine and galantamine), she warned of the impact these can have on other symptoms such as orthostatic hypotension and bradycardia. She also noted that NICE guidance supports use of Memantine for those who cannot support cholinesterase inhibitors.

Ensuring a global and behavioural psychiatric baseline are taken before starting medication is important, as is regular assessment at around 3-6 months after starting or switching to monitor the effect of the medication, and find the best fit for the individual.

In terms of desisting with medication, Alison advised continuing for as long as the drug is clinically helpful to the individual.

Non-pharmacological support can include cognitive stimulation therapy. Alison highlighted the positive evidence base for this (it is recommended by NICE) noting its cost-efficacy and impact on improved quality of life.

Sharing the benefit of things like exercise, social interaction, use of memory aids and such, she also highlighted the importance of ruling out all other potential causes of apparent cognitive impairment including depression, infection or adverse reactions to medications.

Alison was very clear regarding the risks around using antipsychotics, stating the importance of regularly checking with the person afterwards commencing on these. She particularly suggested watching for decreases in ability and motor function.

Sleep

Alison began discussing sleep in light of the many lifestyle changes that can support improved quality of sleep, and emphasising that this is the place to start, ran through the basics of sleep hygiene. Regarding REM sleep difficulties, she recommended removing any mimics and ensuring the sleep space is safe for both the individual and their partner.

In terms of pharmaceutical support, Alison suggested quetiapine taken 30 minutes before bedtime, however noted that it can increase risk of falls and cognitive impairment. She also mentioned the potential benefit of prescribed melatonin but cautioned to ensure that, if this is prescribed in clinic, that their GP is happy to continue the prescription, as this seems to be variable.

Useful tools and tests

• Tym test

• Addenbrooke's Cognitive Assessment,

• DIAMOND Lewy toolkit

Further useful educational resources

• MCI virtual course, session 2 on Lewy body dementia

• Parkinson's Tailored Management Course, module 2, for non-motor symptoms, two sessions of which deal with neuropsychiatry.

Papers cited:

• McKeith IG, Galasko D, Kosaka K et al., Consensus guidelines for the clinical and pathologic diagnosis of dementia with Lewy bodies (DLB): report of the consortium on DLB international workshop. Neurology 1996;47:1113–1124.

• Rollins CPE, Garrison JR, Simons JS, Rowe JB, O'Callaghan C, Murray GK, Suckling J. Meta-analytic Evidence for the Plurality of Mechanisms in Transdiagnostic Structural MRI Studies of Hallucination Status. EClinicalMedicine. 2019 Feb 21;8:57-71. doi: 10.1016/j.eclinm.2019.01.012. PMID: 31193632; PMCID: PMC6537703.

• Williams-Gray CH, Foltynie T, Lewis SJ, Barker RA. Cognitive deficits and psychosis in Parkinson's disease: a review of pathophysiology and therapeutic options. CNS Drugs. 2006;20(6):477-505. doi: 10.2165/00023210-200620060-00004. PMID: 16734499.

Other useful papers

Neurology Today: use of cardiac imaging in LBD diagnosis (2013)