Main symptoms of Parkinson’s disease
Parkinson’s disease (PD) is a slowly progressive degenerative disease of brain. The major symptoms are tremors (shivering), slowness of movements, stiffness and postural imbalance.  These symptoms lead to motor disability and interfere with walking, as well as with other activities of daily living.
Memory impairment in Parkinson’s disease
The mental functions are usually normal in patients with PD, however, 10% of patients can develop dementia (memory impairment along with other cognitive dysfunction), especially in later stages of illness.
What are hallucinations?
Other significant problem in people with PD in later stages is hallucination. Hallucination is often visual. In this condition, patient sees something, which is not there. For example, they may see snakes or lizards in their room (which are not there), and get disturbed with them. They may also see strangers in their house, which are supposedly there to spy on them or harm them. These hallucinations are very upsetting for the patient, making them anxious and depressed. Some patients also have sleep disturbance due to hallucinations.
What are the causes of hallucinations in patients with PD?
1.     Adverse effects of anti-parkinsonian medicines.
2.     Infections such as urinary tract infection or pneumonia,
3.     Side effects of other medications such as pain killers and sleeping pills,
4.     Parkinson’s disease mimic such as Diffuse Lewy body disease (DLBD). In DLBD, patients may have slowness and rigidity (just like PD). However, they have prominent hallucinations and dementia (unlike PD). Moreover, DLBD patients do not respond to levodopa treatment.
Other symptoms of psychosis in patients with PD
1.     Illusions,
2.     Delusions especially paranoid
3.     Confusion,
4.     Sleep disturbance
Delusion refers to a condition where a patient believes in something, even when there is an evidence of the contrary.
How common is psychosis in PD?
About one third of patients with PD suffer from psychosis. So, it is quite common.
How do we manage psychosis in patients with PD?
Management of psychosis can be done in a stepwise fashion as outlined below:
1.     Underlying alternate causes should be looked for and managed. This would include looking for infection and offending drugs.
2.     Comorbid psychiatric conditions, such as anxiety and depression, if present, should be treated.
3.     Minor symptoms such as vivid dreams or minor hallucinations (which are non-disturbing in nature) do not require any treatment.
4.     Anti-parkinsonian drugs should be reduced or stopped. First to eliminate are trihexiphenydyl, amantadine and selegeline/rasagiline. If psychotic symptoms persist, then, the next drugs to be reduced are dopamine agonists (ropinirole and pramipexole), entacapone and levodopa.
5.     In people with cognitive impairment, cholinesterase inhibitors such as rivastigmine or donepezil can be used.
6.     Anti-psychotic medication- quetiapine is the most commonly used.
7.     The first and only FDA approved drug for treating PD psychosis (hallucinations and delusions) is PIMAVANSERIN (Nuplazid). The dose is 34 mg capsules once daily.

Consultant Neurologist
Apollo Hospitals, Hyderabad

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