48 - Other treatments

Other treatments

842 The Maudsley® Prescribing Guidelines in Psychiatry CHAPTER 10 Pimavanserin Pimavanserin is a 5-­HT2A receptor inverse agonist available in the USA and some other countries. It is effective in PD psychosis but has no dopamine receptor activity and does not worsen PD movement disorder or seem to increase mortality.52,53 It is more effective and better tolerated than quetiapine54 and olanzapine.35 Its therapeutic effects seem to increase with the age of the patient.55 Pimavanserin and clozapine are the only drugs unreservedly recommended for PD psychosis.56 A network meta-­analysis suggested only these two drugs had efficacy in PD, while having minimal effect on motor function.49 Clozapine may be effective in pimavanserin non-­responders.57 Cholinesterase inhibitors Cholinesterase inhibitors have been shown to improve cognition, delusions and hallucinations in patients with Lewy body dementia (which has many similarities to PD). Motor function may deteriorate.58,59 Improvements in cognitive functioning are modest.60–62 A Cochrane review and some large RCTs61,63,64 concluded that there is evidence that cholinesterase inhibitors lead to improvements in global functioning, cognition, behavioural disturbance and activities of daily living in PD. Again, motor function may deteriorate64,65 with particular increase in tremor.62 Evidence for memantine is mixed.66,67 Discontinuation of anticholinergic drugs should improve cognition and psychosis – PD patients often have a very high anticholinergic burden, some of this unrelated to the treatment of PD itself.68 Where confounding by indication is removed (where dementia risk could be better explained by indication than a medicine), the classes of medicine with anti-cholinergic properties indicated in dementia are reduced somewhat.69 RCTs are needed to compare deprescribing of maintenance medicines with their continuation in diseases with dementia.5 Other treatments Many patients with PD use complementary therapies, some of which may be modestly beneficial; see Zesiewicz et al.70 Caffeine (and perhaps nicotine)71 may offer a protective effect against the development of PD and also modestly improve motor function in established disease.72 Box 10.4 summarises the treatment of PD. Box 10.4  Simplified summary of treatment in Parkinson’s disease Depression in PD Sertraline is first choice. Venlafaxine and duloxetine are next option. Consider agomelatine or bupropion. Pramipexole is an option in those not already on a dopamine agonist. Psychosis in PD Try low-­dose quetiapine but withdraw if ineffective. Clozapine is the drug of choice for PD psychosis. Pimavanserin may be used where available. Electroconvulsive therapy is a last resort.