Understanding Parkinson’s Disease Psychosis

What is Parkinson’s Disease Psychosis?

As Parkinson’s Disease progresses, up to 40 percent of the approximately one million Americans living with the illness will develop psychotic symptoms, primarily hallucinations, but also delusions. These symptoms can be an indication of Parkinson’s disease psychosis (PDP), but unfortunately, many patients are not diagnosed. Sometimes, the symptoms of PDP are misdiagnosed. Other times, patients and their families may not be comfortable sharing the symptoms with their physician team.

What Causes PDP?

Though definitions can vary, the term psychosis generally means “loss of reality testing.” Psychotic symptoms may be brought on by infections, typically bladder or pneumonia, but are often caused by medications. These are usually the ones used in treating PD, but other medications, particularly narcotic pain medications and many of the drugs used to treat an overactive bladder, may cause symptoms as well. When infections have been ruled out and no other medication has been identified as causing the psychosis, then the most likely culprits are the Parkinson’s Disease medications. It’s also possible that PDP might be a naturally occurring complication as the disease progresses.

There are a couple of things to keep in mind here. One is that the symptoms may begin even though Parkinson’s Disease medications have been constant over several months, or even years. The problem may not necessarily be triggered by an increase in Parkinson’s Disease medications. The reason that a stable medication regimen can begin causing hallucinations is that the Parkinson’s Disease is always progressing, making patients more sensitive to possible drug side effects. The second principle to keep in mind is that it may not be one drug that is the cause, but the combination of all the Parkinson’s Disease medications.


Many people living with Parkinson’s Disease have occasional, or not so occasional, symptoms that are often seen in people who lose their ability to separate reality from fantasy. These are most commonly hallucinations, which are false perceptions in one of our special senses (vision, hearing, taste and touch). For example, it’s quite common to report seeing other people, often children, who are sitting or standing in the room, ignoring them. Another commonly cited experience is that a patient who is watching TV or reading a book notices two strangers sitting on a sofa talking to each other, but they make no noise. The patient talks to them, and they ignore him. When he gets up to approach them, they disappear. A few days later, this happens again, and after one or two episodes, the patient no longer pays attention or tries to contact them. These types of hallucinations tend to occur more at night than during the day and are usually the same each time.

Auditory hallucinations, or hearing things that are not there, are about half as common as visual hallucinations, and they tend to be less distinct than the visual hallucinations. Patients may hear a radio in another room, a party going on across the street or voices talking in the hallway. Less common are tactile hallucinations (e.g., feeling things on the skin), olfactory (e.g., smelling an aroma not detectable to others) and taste hallucinations.

Other Types of Hallucinations

In addition to persistent or repeated visual hallucinations, a Parkinson’s Disease patient might also see a fleeting image out of the corner of their eyes, like a cat or a shadow passing by, but when they turn to look, there isn’t anything there. Sometimes they see slight flashes of light, which are very much like reflections off their eyeglasses. A “presence hallucination,” is another type of experience which is not really a hallucination. With a presence hallucination, patients have a strong feeling of another person, or an animal, being behind them or to the side, but when they turn around, there isn’t anything there. This is a strong feeling – something most people have experienced on occasion – but in this case, it’s experienced more frequently and more strongly.


Delusions are false, irrational beliefs. In PDP, delusions are more bothersome, but less common. Also, in PDP, the delusions tend to be fairly similar from one person to the next and are usually paranoid in nature. For example, a patient might be positive that his spouse has been attacked and is in need of assistance. Or, a spouse may be irrationally convinced that their partner is committing adultery.

Susan’s Story

Sadly, after a 20-year battle with PD, Susan’s father, Gary, passed away in April 2014 at the age of 74. Because Susan resides in Las Vegas, her mother, Marjorie, was her father’s primary caregiver in Iowa. Susan stayed actively involved by providing her mom with emotional support, particularly in later years when her father developed PDP. Susan and her mother believe that Gary’s PDP started after a hospital stay resulted in changes to his medication doses. At that time, Gary began to experience strange and disturbing delusions, often in relation to his wife’s safety. For example, on several occasions, he called the police, convinced that “weirdos” had entered the house to sexually assault Marjorie. Also disturbing, Gary would see kittens frolicking and become upset thinking he saw them die because he “forgot” to feed them. Other hallucinations included seeing strangers in his bed or in the shower. Despite telling Gary that his visions were not real, Susan and Marjorie often could not convince him of the truth. Susan’s mother was emotionally exhausted and stressed from caring for Gary. The idea of seeking more help for him was overwhelming, given the time she already gave to physical therapy and day-to-day care. Her life already revolved around Gary’s illness. Susan tried to encourage her mother to speak to her physicians about Gary’s visions, but her mother was embarrassed. Both also wished the physicians had asked if these symptoms were occurring.

PDP’s Impact on Caregivers

As Susan’s story demonstrates, PDP is difficult for both the patient and their caregivers, particularly because it is impossible to convince someone that their delusions are not real. Logic does not penetrate. In fact, accusations of spousal infidelity are often the “last straw” when caregivers find caring for their loved one too overwhelming. One of the major problems in dealing with PDP is that the patient and the family often try to hide the problem – the patient for fear of being thought “crazy” and the caregiver due to embarrassment. The reality is that when a Parkinson’s Disease patient has psychotic symptoms, his or her mental abilities will be otherwise normal. The patient may not be disoriented, can still balance their checkbook and recall everything they’re supposed to know. When hallucinations or delusions occur, the treating doctor should be notified. No irreversible harm will occur if treatment is delayed, but it is unlikely the problem will go away on its own.

Treating PDP

Hallucinations don’t always need to be treated. If these symptoms often don’t bother the patient, then they don’t need immediate attention, but they should always be monitored. Yet, hallucinations also indicate toxicity, hence Parkinson’s Disease medications cannot be increased without worsening of the hallucinations, and therefore, physicians may limit treatment. When the psychotic symptoms require treatment, the doctor may first reduce Parkinson’s Disease medications, and when these cannot be further reduced, they may prescribe the only currently available antipsychotic drugs that do not worsen mobility in people with PD. When these drugs are successful, then the Parkinson’s Disease medications can be increased, if needed, to better control Parkinson’s Disease motor symptoms.

Support Your Loved One and Yourself

PDP is also associated with increased caregiver stress and burden, nursing home placement and increased morbidity and mortality. But, your loved one is certainly not alone in living with PDP, and an effective management plan can improve the complications. Seek out the support that he or she needs, but also make sure that you are getting the emotional care you personally need in order to be an effective advocate for your loved one.

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