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Psychosis in Parkinson’s Disease


Not many people are aware that in addition to the body, Parkinson’s Disease (PD) also affects the mind and soul. Psychosis is quite common in PD, occurring in up to 30% of Parkinson’s patients, leading to reduced quality of life, early institutionalization and increased death rate.1 Psychosis refers to a mental condition in which the main feature is abnormal thought process that manifests as hallucination (seeing non-existent people or objects), confusion and delusion (a firm but false belief of being persecuted or harmed by others).

Psychosis in PD is commonly a side effect of PD medications. It is a significant source of distress for caregivers, as illustrated by the following true stories (all the names in this article are not real).

Patient 1

Mr. Yee, a 72-year-old Chinese man, had just undergone brain surgery (Deep Brain Stimulation) after suffering from PD for thirteen years. He was happy with the outcome of the brain surgery, as his body movement had improved a lot. He was quite independent in carrying out his daily activities despite taking a much smaller dose of medications. His wife, Mrs. Yee, was also happy that her husband had done well following the brain surgery. She was grateful that her husband had been given a new life after the successful surgery.

The couple did have a better life after the brain surgery, but not for long. Over the past three months, Mr. Yee had not been able to sleep well, and so did his poor wife.

Mrs. Yee, a 70-year-old housewife, had been a very loving and supportive spouse all these years. But recently, she had been really shaken by her husband’s odd behaviour. Her patience had been stretched to the limit by her husband’s accusations – that she was having an affair with her “former boyfriend” whom she had met in secondary school (paranoid delusion).

Each time she received phone call, Mr. Yee became so suspicious that he confronted his wife. He would insist that he follow his wife to the market (or even anywhere), fearing that she would meet her “lover”. And whenever she denied having any “affair”, it led to heated arguments.

“My husband is definitely out of his mind! Who would be interested in a 70-year-old lady like me? My ex-boyfriend is already 75, and has just suffered from stroke one year ago,” lamented the poor lady.

“My dad used to be a wonderful and gentle person who was very careful with whatever he said. For the past one month, he was not his usual self at all. Before I left home early in the morning, he would come up to me and tell me that it was best that he died, without any apparent reason. I think he just wanted to make me feel guilty,” said Kevin, the eldest son.

Mr. Yee often peeped out through the window, looking for “strangers” whom he said would lay their hands on him (paranoid delusion). Whenever he heard the sound of cars passing by his house, Mr. Yee would rush to the window to “protect” his home. “I saw a few weird-looking men sitting in the living room (visual hallucination). I think they are here to finish me off,” Mr. Yee frantically told his family.

One morning, Mr. Yee suddenly woke up from sleep and screamed, “Help! I saw a large animal with black furs on the floor (visual hallucination)! It bit me on the foot!” But his wife did not see anything unusual at all on the floor.

When Mrs. Yee could not tolerate her husband anymore, she finally came to my clinic to seek help. Suspecting that he had mental side effects due to his PD medications, I reduced the dose of Madopar, and stopped Comtan (Entacapone) and Jumex (Selegiline). “The reduction in PD medications is an important step in treating his mental symptoms, but at the expense of his body movement (which would slow down). In the present situation, treating the mind is the priority. The slowing down of his body movement is something temporary,” I explained to Mr. Yee’s family.

“I will start him on Seroquel (Quetiapine), a medication which is effective in treating his mental symptoms. After a period of one to two months, when Mr. Yee’s mental disturbance has subsided, we can increase the dose of his PD medications again. Eventually, he will have a strong body and healthy mind,” I added.

Over a period of five weeks, Mr. Yee’s mental symptoms had dramatically improved. He no longer accused his wife of adultery, and could sleep well again. But on and off, he still saw some “strangers” at his home. Nevertheless, this time he was not troubled by the “strangers” anymore because he knew “they” were not real.

As I increased the dose of Madopar and restarted Comtan, he gradually regained his physical strength. He continued taking Seroquel till today, in order to control his mental symptoms. And finally, the whole family could sleep in peace.

Patient 2

Mr. Nathan was a 61-year-old Indian man who been treated for PD over the past five years. He was responding well to Artane (Benzhexole) and Trivastal (Piribedil). He could drive alone to work everyday.

Over the past two months, his wife noticed that he frequently stood near the window, looking out towards the main road in front of his house. Initially, he did it only in the evening. But over the past two weeks, he was there next to the window for almost the whole day, including midnight. When his wife asked what he was doing near the window, he just kept quiet. She was puzzled as she did not understand her husband’s bizarre behaviour.

He often called his wife in her office to ask whether she was alright and “safe”, which was considered unusual by his wife. Even his daughter received frequent phone calls from him while she was in school.

One week before Mr. Nathan and his wife came to my clinic, he had become so restless that he couldn’t sleep or eat. When his wife tried to speak to him, he could not communicate at all. Instead, he was uttering nonsensical words to himself. He looked very disturbed and preoccupied with the idea of “some people coming to the house” (paranoid delusion). And his wife started hearing him say, “I saw them (visual hallucination). They are here to kill us”.

As he was in such a confused state, I admitted Mr. Nathan to the ward. I replaced his medications (Artane, Trivastal) with Requip (Ropinirole), a new medication for PD. In addition, I asked him to take Seroquel (Quetiapine) for the treatment of his mental symptoms.

Mr. Nathan’s mental complication was actually the most difficult case I had ever handled. He did not trust me or any nurses at all, fearing that we were trying to “poison” him (paranoid delusion). Persuading him to take his medications was really challenging – I had to sit at his bedside to reassure him that the medications were not “poison”. He even asked me to check on the security guards in the hospital, to determine whether they were “trustworthy”.

A very remarkable incident took place one morning, when I was conducting my morning ward round. As I walked into Mr. Nathan’s room, he placed his index (second) finger on his lips and whispered, “Sshhh.. I saw them hiding in the bathroom (visual hallucination).” When I asked him why these “people” were there, he pointed his finger to his head and said, “they are here to kill me (paranoid delusion).

At times, Mr. Nathan became so restless that I was forced to administer sedative medications by injection (once, I myself had to do this while he was restrained by two nurses). He kept on mumbling these words to himself, “they are here�they are here.”

After undergoing treatment for about two weeks in the ward, Mr. Nathan’s condition improved. I sent him home with the same medications.

Two months later, he recovered completely. His nightmare had ended. He was back to his usual self again, and started driving to work as he used to do. He continued taking Requip and Seroquel till today.

Patient 3

Mdm. Rokiah, a 65-year-old Malay lady, had been taking Artane (Benzhexole) and Jumex (Selegiline) for four years. Her PD was fairly well-controlled. But lately, she had been feeling “disturbed”. When asked to elaborate on her problem, she said, “at times, when I am alone in the room, I can see strangers flying fast across the room (visual hallucination). When they reach the other end of the room, they just disappear into thin air.”

Patient 4

Mdm. Siti, a 42-year-old Malay lady, had suffered from PD since the age of 37. She had been doing well with Stalevo and Artane (Benzhexol). However, over the past two months, she had become depressed. She often cried when she was alone in the home. She also lost her appetite and could not sleep well.

Her husband had been very supportive of her all these years. Even though he had tried his very best to console his wife, occasionally he lost his patience. Once, when he asked his wife what was wrong, she said, “Someone told me that you are thinking of divorcing me (auditory hallucination). You are planning to send me to the nursing home because I am just a burden to you.” And when he angrily denied this, his wife pulled out a knife and threatened to stab him.

Puzzled by the recent change in his wife’s behaviour, he finally brought her to my clinic.

“I feel like dying. There is no point in me living this life. I am a burden to everyone. I won’t even live long enough to see my daughter growing up,” said Mdm. Siti as she sobbed.


Most commonly, psychosis present as visual hallucinations.

A common form of mental side effects in PD is visual hallucination, a condition in which patients report seeing objects, animals or people who are actually non-existent. Auditory hallucination (hearing voices of non-existent people) is rarely seen in PD.

Most patients are not aware that they have hallucination – they really believe that the “strangers or animals” that they see are real. In these cases, patients usually need medication to treat hallucination, especially if whatever they “see” is frightening.

On the other hand (fortunately), there are also some patients who actually know that the hallucination is not real. Somehow, these patients gradually learn to ignore or live with the hallucination, As such, they may not need medications to treat the hallucination.

Another form of mental side effects in PD is paranoid delusion, a condition in which the affected patients have a firm (albeit false) belief that some people (including spouses and family members) are out to harm them or being dishonest to them. An interesting observation is that paranoid delusion in many male Parkinson’s patients manifest as pathological jealousy – a firm conviction that the wife is having affair with other men.

Mental side effects of medications in PD are treatable, and usually completely reversible. Every single medication for PD can cause these mental side effects. Medications such as Zyprexa (Olanzapine) and Seroquel (Quetiapine) are effective in treating mental side effects due to PD medications.

As illustrated above, the caregivers often experience enormous stress caused by these mental side effects, especially the pathological jealousy. I think it helps to reduce the caregivers’ pain if they understand that the abnormal behaviour of affected Parkinson’s patients is purely due to the medications, not intentional. They just have to bear with the unpleasant experience while the mental side effects resolve with treatment, usually over one to two months period.


1. Factor SA, Feustel PJ, Friedman JH, et al. Longitudinal outcome of Parkinson’s disease patients with psychosis. Neurology 2003 ; 60 : 1756 – 1761.