Parkinson’s disease, hallucination linked

Parkinson’s disease (PD) is a neurodegenerative disease of the brain. Like other neurodegenerative diseases, this disease has a predilection to certain group of nerve cells that produce dopamine.

Parkinson’s disease is commonly known as the disease of tremors. Not only tremors or movement, the patient shows other symptoms which are referred to as non-motor symptoms, which may precede the onset of tremors by even more than 10 years. These include a reduced sense of smell, sleep disturbances (insomnia, frightening dreams, enacting dreams), memory loss, depression, constipation, difficulty in holding urine, sexual dysfunction etc.

Hallucinations are false perceptions created in a person’s mind. A person having a hallucination may see, hear or feel things that are not actually happening.

Visual hallucination is one of the most distressing symptoms for any patient, it becomes more distressing especially when the patient believes it to be true. Visual hallucinations may range from very simple unformed to very vivid visual images causing significant anxiety to the patient, as well as his caretakers. At times, patients may shy away from reporting them, thinking that they will be branded as ‘insane.’ According to the National Parkinson Foundation, visual hallucinations can be a complication in Parkinson’s disease. Around 17 to 72% of patients with PD have also been diagnosed with visual hallucinations. A Parkinson’s disease patient has a lifetime risk of around 45% of getting visual hallucination.

Causes of visual hallucinations in PD: a) Disease-induced: The factors which increase the chance of having disease-induced visual hallucination are the presence of cognitive impairment, higher stage of PD, longer duration of the disease, presence of depression and sleep alterations. b) Drug-induced: There are various types of medications given for PD, which also differ in their capacity to produce visual hallucination. The most commonly implicated drugs are Amantadine, pramipexole and levodopa.

Visual hallucinations may be minor or complex in nature.  Minor visual hallucination includes, presence hallucination — feeling someone is beside or behind the patient. Passage hallucinations — feeling that some animal or person just passed by the patient. String hallucination — subject may find that there are long strands of thread or skin extending from his or her fingers.

Complex visual hallucination includes, formed visual hallucination — clearly seeing non-existent human/demons/other peculiar creatures. Many a times patients get the feeling of living in a fantasy world, and at times, may even tend to interact with them.
Multi-modal hallucination — along with visual hallucination, the patient may also hear a non-existent person speak to them, feel someone is touching and perceive non-existent odours like some aromatic food.

Whenever a patient with PD develops visual hallucination, it is required for the doctor concerned to attain a detailed medical history of the patient, along with the knowledge of the nature of hallucination, severity and its probable aetiology, duration of the disease, severity and stage, and the extent of cognitive decline. There are many other diseases which can be present with visual hallucination which have to be ruled out. In fact, if visual hallucination occurs within one year of course of the disease, then other diseases may also be considered like dementia with Lewy Bodies.

Treatment

Depending on the scenario, the visual hallucination might respond to dose adjustment of medication for PD. Medications like Amantadine, pramipexole have strong predilection to cause visual hallucination. Hallucinations  may reduce with dose reduction. Non drug-related visual hallucination may require addition of other medications like acetylcholine esterase inhibitors and anti-psychotics. As anti-psychotic drugs can worsen PD, safer anti-psychotics like clozapine, quetiapine etc can be used.

The patient and their caregivers need to be aware of this issue. The patient should be encouraged to speak up regarding any such symptoms, especially by family members, and report to the doctor at the earliest. The medications for visual hallucination may need to be given slowly. Hence, the patients and their caregivers need to understand the need for multiple visits to the doctor.

To conclude, visual hallucination in Parkinson’s disease requires much more attention and awareness. Timely intervention by experts (movement disorder specialists/neurologists) may help prevent significant stress to the patients and their caregivers.

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(The writer is consultant, Neurology, Narayana Health City)

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