44 - Depression

Depression

840 The Maudsley® Prescribing Guidelines in Psychiatry CHAPTER 10 Parkinson’s disease Psychiatric comorbidity is common in Parkinson’s disease (PD). Approximately 25% of PD patients will suffer from major depression, a further 25% from milder forms of depression, 25% from anxiety spectrum disorders and 25% from psychosis.1–3 The risk of developing dementia is 3.5–6-­fold higher, depending on definition, than in age-­ and gender-­matched controls.4 Depression and anxiety often precede PD diagnosis. Anti-­parkinsonian treatment is likely to increase psychiatric comorbidity. Indeed treatment-­linked prolonged cognitive processing may be a harbinger of more disabling morbidity, like deficits in attention, multitasking and difficulties in sequencing and planning.5 While depression and anxiety can occur at any time in the course of PD, psychosis, dementia and delirium are more prevalent in the later stages of the illness. Close co-­operation between the psychiatrist and prescriber of anti-­parkinsonian ­medication is often required to optimise treatment for this group of patients. Depression Depression in PD predicts greater cognitive decline, deterioration in functioning and progression of motor symptoms,6 possibly reflecting more advanced and widespread neurodegeneration involving a variety of neurotransmitter pathways7 and/or inability/ disinclination to seek or comply with remedial therapies. Depression may also occur after the withdrawal of dopamine agonists.8 Similarly, cyclical mood changes follow the on/off fluctuations associated with the levodopa dosage cycle. Suggested treatments are described in Table 10.13. Table 10.13  Recommendations for treatment of depression in Parkinson’s disease (PD). Step Intervention Exclude/treat organic causes such as hypothyroidism (the prevalence of which is relatively high in PD6). SSRIs are considered to be first-­line treatment although the effect size is modest.9–11 Some patients may experience a worsening of motor symptoms,12,13 in particular tremor. Sertraline is the preferred SSRI in PD.14 Care must be taken when combining SSRIs with selegiline (or rasagiline), as the risk of serotonin syndrome is increased.6 The SNRIs venlafaxine15 and duloxetine16 also appear to have some effect although venlafaxine may modestly worsen motor symptoms.15 TCAs are generally poorly tolerated because of their anticholinergic (can worsen cognitive problems and constipation) and alpha-­blocking effects (can worsen symptoms of autonomic dysfunction). A 2022 network meta-­analysis17 showed that dopamine agonists and SSRIs have the highest efficacy and acceptability. Limited evidence supports the safe and effective use of agomelatine,18,19 bupropion20 and vortioxetine.21 Consider augmentation with dopamine agonists/releasers such as pramiprexole.22 Note though that these drugs increase the risk of impulse control disorders.23,24 They have also rarely been associated with the development of psychosis.25 Dopamine agonists are effective antidepressants when used as a single agent.26 Consider ECT. Depression and motor symptoms generally respond well6 but the risk of inducing delirium is high,27 particularly in patients with pre-­existing cognitive impairment. Follow the algorithm for treatment-­resistant depression (see ’Drug treatment of depression’ in Chapter 3) from this point. Be aware of the increased propensity for adverse effects and drug interactions in this patient group. TCAs, tricyclic antidepressants.