Depression, dementia and psychosis are the three main mental health problems associated with Parkinson's Disease.
Between 40 and 50% of people with Parkinson's disease will be affected by depression during some stage of the illness. Most cases will be mild to moderate but some people do experience more severe forms of depression.
It is not clear what the exact relationship between Parkinson's and depression, what does seem clear is that the depression should not simply be thought as a reaction to the disabling effects of the condition.
Depression is characterised by low mood, loss of interest and enjoyment and fatigue together with combinations of:
Poor concentration, poor memory, excessive worry, feelings of worthlessness, hopelessnes and guilt, negative views of self and life and suicidal thoughts are all features of depression when the cognitive functions are disturbed.
The NICE guidance names the following factors as possible causes of depression in people with Parkinson's-
The NICE guidance does not make any specific recommendations for the treatment of depression other than to suggest that doctors should have a "low threshold" in diagnosing depression, should be mindful of the overlap between symptoms of mild depression and those of Parkinson's Disease and should tailor each type of treatment to the individual taking into account the medication that has been prescribed for the motor features of Parkinson's.
The Parkinson's Disease Society's factsheet on depression lists tricyclics, SSRIs and some antidepressants with other mechanisms as being appropriate for the treatment of depression.
The NICE guidance states-
"There is insufficient evidence from RCTs (randomised controlled trials) of the efficacy or safety of any antidepressant therapy in PD. This includes cognitive behavioural therapy, all classes of antidepressant medication and electroconvulsive therapy......There is an urgent need for further research to establish effective and safe treatments for depression in PD."
Psychoses
Psychoses are characterised by delusions and hallucinations. People with Parkinson's may experience psychotic symptoms at any stage during the illness. 50% of people with Parkinson's will experience some psychotic symptoms and 30% of people may experience some kind of hallucinations within the first five years.
Visual hallucinations (seeing things that aren't there) are the most common form of hallucinations but people with Parkinson's can also experience auditory hallucinations (hearing things that aren't there).
Delusions (believing things that have no basis in reality) are much less common than hallucinations but they may involve feelings of persecution, irrational jealousy etc.
Many people find these psychotic symptoms very distressing. Doctors should take time to explain the nature of these symptoms to both people with Parkinson's Disease and their carers.
The NICE guidance advises doctors to evaluate psychotic symptoms with care and to try and work out whether they are caused by:
In terms of treating psychotic symptoms, doctors are advised to consider slowly withdrawing the anti-Parkinsonian medication which may have triggered the psychoses. This may mean reducing the anti-parkinsonian drugs to levodopa only. The guidance also makes the point that mild psychoses need not be treated at all if they are "well tolerated by the patient and carer". The guidance recommends that Clozapine may be used to treat the psychoses but warns that registration with a mandatory monitoring scheme is required. Typical anti-pyschotic medications should not be used as they worsen the physical aspects of Parkinson's. The Guidance says that atypical anti-psychotics can be used but that there is only limited evidence for their usefulness.
Dementia
Dementia is defined as the progressive loss of global cognitive function where the brain becomes less and less able to function. Dementia in people with Parkinson's is relatively common- it is estimated that between 48 to 80% of people with Parkinson's may develop dementia during the course of the illness.
The NICE guidance makes the point that dementia is invariably accompanied by a reduced quality of life for patients and their carers.
With regard to treatment, the assessment and management of dementia requires input from a multidisciplinary team. NICE recognise that cholinesterase inhibitors have been used succesfully in some Parkinson's patients with dementia but that further work needs to be done to identify those patients who will benefit.
