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A very significant subset of Parkinson's disease patients develop dementia at some point during the course of their condition. How can dementia best be managed in people with Parkinson's?

While Parkinson's disease is considered a movement disorder and people think mostly of motor symptoms when they hear the word "Parkinson's", the condition features many non-motor symptoms too. Depression, anxiety, fatigue, and disordered sleep are, for instance, very common among patients. 

Cognitive problems such as memory loss and clarity of thought aren't among the diagnostic criteria for Parkinson's, but a significant subset of patients will develop them at some stage. Somewhere between half and 80 percent of Parkinson's patients will also develop Parkinson's dementia over time, especially once they reach the later stage of the disease, and faulty protein deposits in the brain called Lewy bodies play a large role in this. Your doctor will be able to diagnose dementia, but should seriously consider alternative problems that can lead to very similar symptoms, such as depression and side effects of Parkinson's medications. Memory and cognitive tests can help your healthcare provider determine what you are dealing with, but common symptoms of Parkinson's dementia include:

  • Forgetfulness
  • Slowed thought processes
  • Trouble communicating effectively, both because of cognitive decline (which can manifest as finding it hard to come up with the right words) and because speech may become slurred
  • Impaired problem solving and abstract thinking skills
  • Inability to concentrate

An irritable mood, sudden mood swings, personality changes, sleepiness, depression, hallucinations, and delusions are commonly seen in patients with Parkinson's dementia as well. As the symptoms gradually grow worse, independent living will become more difficult and eventually impossible. 

Like Parkinson's disease itself, there's no cure for Parkinson's dementia — and treatment approaches seek to minimize symptoms. What are the best ways to manage dementia in Parkinson's disease patients?

1. Cholinesterase inhibitors

Cholinesterase inhibitors, the main kind of medication used to fight cognitive decline in people who were diagnosed with Alzheimer's disease, will be considered for a person diagnosed with Parkinson's dementia too. The two drugs doctors are most likely to suggest are:

  • Rivastigmine can help reduce confusion, boost memory function, make the patient more alert, and allow them to engage in everyday tasks more easily. It works by seeking to restore your natural brain chemistry (neurotransmitters), and is generally considered to come with a low risk of side effects.
  • Donepezil boosts cognitive function (thinking skills) and may slow cognitive decline, and is often used in people with Lewy body dementia. Research shows that this drug may be beneficial for Parkinson's patients who experience hallucinations, though further study is required. 

2. Atypical antipsychotic drugs

More traditional antipsychotics, which have been on the market for a longer period of time, can pose a real danger to Parkinson's disease patients. While they're not infrequently used in the treatment of Alzheimer's disease, research suggests that up to half off people with Parkinson's and Lewy body dementia suffer intolerable side effects when they take typical antipsychotics, which can include:

  • An extremely confused state of mind
  • Alterations in consciousness
  • Delusions and hallucinations — the very things they are meant to help treat
  • Trouble chewing and swallowing
  • More intense symptoms of Parkinson's disease

Newer, so-called atypical, antipsychotics eliminate some of these struggles, and doctors may consider prescribing:

  • Clozapine — considered effective for Parkinson's-related psychosis, the health and wellbeing of patients taking this drug needs to be monitored extremely closely. That is because it can cause dangerously low white blood cell counts (agranulocytosis), as well as heart and kidney problems. Patients may also have a higher risk of developing blood clots. 
  • Quetiapine — though some studies find it is just as effective in treating psychosis, others have shown less promising results. 
  • Risperidone and olanzapine do a good job treating delusions and hallucinations, but are associated with increased motor function. 
  • Aripiprazole — though commonly prescribed to people with psychosis related to other causes, Parkinson's patients do not do well on this drug.

Neuroleptic malignant syndrome — which manifests as a high fever, rigid muscles, and the loss of muscle tissue — is a rare but potentially deadly complication of taking antipsychotics. 

3. Selective serotonin reuptake inhibitors (SSRI antidepressants)

Antidepressants may play a key part in managing dementia as many sufferers are depressed. SSRI antidepressants are the most commonly used kind. Though Parkinson's patients generally tolerate them well, some find that SSRIs worsen their motor symptoms.

The following SSRIs may be considered:

  • Fluoxetine (Prozac)
  • Sertraline (Zoloft)
  • Escitalopram (Lexapro)
  • Citalopram (Celexa)
  • Paroxetine (Paxil, Pexeva)
  • Vilazodone (Viibryd)

4. Clonazepam to treat REM behavioral disorder

REM behavioral disorder, or RBD, is a common complication of Parkinson's disease in which patients act out their — often extremely vivid — dreams. This may cause the patient to hurt themselves while sleep, but it also means they can pose a danger to their partner as they become violent as they sleep. 

Clonazepam, an anti-sezure medication, has shown to do a very good job at reducing the symptoms of REM behavioral disorder, even in very low doses — one study shows that up to 80 percent of patients taking this drug enjoy complete symptom relief, while a further third has reduced symptoms. It can, on the other hand, have its own set of side effects, in the form of dizziness, drowsiness, and increased motor problems.

5. What drugs should people with Parkinson's dementia stay away from?

Some anticholinergic drugs — a kind of medication often prescribed to people with Parkinson's — can induce hallucinations and psychosis in Parkinson's patients. Even the common antihistamine Benadryl can do the same thing. These are exactly the kinds of additional problems a person already dealing with dementia doesn't need, and it's also important to be aware that some anti-anxiety drugs do exactly the opposite of what they're intended to do in dementia patients.

In people with dementia, it is best if a carer (a professional or a loved one) can keep track of the symptoms and difficulties that may pop up, and then informs the treating doctor so a solution can be found. 

6. What can carers do to help people with Parkinson's dementia?

Parkinson's dementia quickly makes independent living impossible, and carers will play a large role in maximizing patients' quality of life. The better you understand Parkinson's and dementia, the better you'll be able to help your client or loved one. 

Steps that can help you help the patient with physical tasks include:

  • Installing handrails — the bathroom is a key spot for this, but hallways and bedrooms are other possible "targets".
  • Make sure anti-slip mats are in place to help prevent falls.
  • Accompany the patient to gentle exercise activities that will foster independence and improve physical symptoms.
  • Assist the patient in getting dressed as they are seated, on a bed or chair.
  • Though it may be easier and faster for you to complete daily care tasks almost entirely for the patient, include them in their own care as much as possible.

Tips that will benefit the patient cognitively include:

  • Creating a set routine that the patient can rely on and that may help them remember — the timing of medication, meals, personal hygiene, fun, and physical activities should all be planned out. Write all this down on a big calendar to help them remember.
  • Make sure the patient has the opportunity to engage in mentally stimulating activities. 
  • Patients with delusions, hallucinations, paranoia, or aggressive tendencies can be very hard to care for. Keep in mind that these things are symptoms of an illness, not a true relfection of who the person is, or was. 
  • If you're a relative, make sure that you take time for yourself as well — share your responsibilities with others. Carer burnout is a very real phenomenon, and not only will it drive you crazy, it will also impact the quality of care your loved one receives.

  • Samuel, M., Maidment, I., Boustani, M., & Fox, C. (2006). Clinical management of Parkinson’s disease dementia: pitfalls and progress. Advances in Psychiatric Treatment, 12(2), 121–129.
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