Visual Hallucinations in Parkinson’s disease
Parkinson’s disease has gotten a lot of media attention in the past year. Michael J. Fox has brought remarkable attention and funding to the disease since his diagnosis in 1992. He sparked a lot of conversation regarding treatment and research about Parkinson’s in 2013 when he starred in the NBC show The Michael J Fox Show. 2014 however brought new light to Parkinson’s disease in the media when it was made public that prior to his suicide, Robin Williams was diagnosed to be in the early stages of Parkinson’s disease. Unfortunately since then there has not been much light shed publically about the treatment of psychiatric illnesses in patients already or newly diagnosed with Parkinson’s disease.
Parkinson’s disease is a degenerative disease that’s primary effect is on the motor function of the patient. This does not mean that symptoms are limited to motor function, both emotional and social functioning can be markedly impaired as well. Recently literature has started suggesting that the non-motor symptoms associated with Parkinson’s disease are more debilitating than the motor symptoms. Psychiatric care within Parkinson’s disease encompasses emotional disturbances such as anxiety and depression, psychosis, and sleep disturbances. With all psychiatric care behavioral modifications should be part of a well-rounded treatment plan, however for this post the focus will be pharmacologic management of symptoms with the neurobiology of the symptoms specifically taken into account. In a literature review done by Dr. Rosa Quelhas in 2013, it was shown that there are numerous studies showing the effectiveness of medications on the differing psychiatric concerns for each patient. Anxiety, depression, sleep, and psychosis are all approached slightly differently in Parkinson’s disease because of the neurobiological differences in the Parkinsonian brain.
According to Quelhas psychosis is one of the most common and well-studied psychiatric concerns in Parkinson’s disease. Psychosis could be attributed to the long-term use of anti-Parkinsonian medications, older age of patients, longer disease duration, comorbid depression, and/or comorbid dementia (Quelhas, 2013). Psychotic symptoms in Parkinson’s disease are typically visual hallucinations, many times which are not emotionally driven. Kiferle et al. in their article about visual hallucinations in Parkinson’s disease patients found through SPECT studies numerous areas of the brain were activated. These areas of the brain included the posterior cortical areas which are involved in visual perceptions as well as significantly less activation in numerous regions of the frontal area of the brain (Kiferle, 2014). These frontal areas of the brain where there is less activation in patients suffering from Parkinson’s are the areas that have been associated with attention- meaning that decreased activation in these areas might put patients at an increased risk for visual hallucinations. The basal ganglia’s involvement in the development of visual hallucinations has also been the subject of several studies. This is probably because of the interactions between the basal ganglia and the fronto-striatal circuits connecting it to the frontal areas. fMRI studies have shown that patients with visual hallucinations had increased caudate nucleus uptake reduction, again pointing to dopamine in the Parkinsonian brain.
Treatment of psychiatric symptoms in Parkinson’s has to take into account the neurobiology of Parkinson’s disease and the mechanism of action of the medications. Something that also needs to be taken into account are the motor symptoms that the patient most likely already has due to Parkinson’s and being careful to not exacerbate those symptoms. This is readily taken into account when considering first-generation antipsychotics in Parkinson’s disease. It has been shown that typically patients cannot tolerate first-generation antipsychotics because high doses tends to produce extrapyramidal symptoms while lose dose first-generation antipsychotics tend to have significant side effects that patients find intolerable.
Clozapine, a second-generation antipsychotic, has been shown in numerous drug trials and studies to be an effective agent in treating the psychotic symptoms in patients with Parkinson’s disease without exacerbating motor symptoms. It has been claimed to be the “gold standard antipsychotic treatment” (Quelhas, 2013) for psychotic symptoms. According to the review done by Quelhas, clozapine has also been shown in several studies to have a benefit in improving other symptomatology in Parkinson’s disease such as akathesia, dystonia, and neurogenic bladder. The efficacy of clozapine in Parkinson’s disease has been of great interest in the past couple years because while it is a non-selective antagonist of both serotonergic and dopaminergic receptors its exact mechanisms are not currently fully understood. Clozapine has been shown in studies to have an anti-tremor property as well, which makes it an excellent choice for the treatment of psychotic symptoms because it has been shown to cause reductions in the prescribing cascade- meaning that the number of medications prescribed to treat the side effects of another prescribed medications is reduced. This both could streamline a patient’s medication regimen as well as promote medication regimen adherence. Fewer individual medications and a lower side effect profile of all medications has been shown to increase patient satisfaction with their care (Toure et al, 2006).
Mirtazapine was shown to have specific efficacy in the treatment of visual hallucinations in a case report published by Tagai et al. in 2013. The article discussed the criteria for psychosis within the population of patients suffering from psychosis, including visual hallucinations. Tagai et al recognized that while the underlying neural biology of psychotic symptoms in Parkinson’s disease is still largely unclear, mirtazapine appeared to target both the serotonin and acetylcholine receptors that play an emergence in the visual hallucinations.
Kiferle, L., Ceravolo, R., Giuntini, M., Linsalata, G., Puccini, G., Volterrani, D., & Bonuccelli, U. (Jul 2014). Caudate dopaminergic denervation and visual hallucinations: Evidence from a 2I-FP-CIT SPECT study. Parkinsonism & Related Disorders, 20, 761-765. doi:http://dx.doi.org/10.1016/j.parkreldis.2014.04.006
Quelhas, R. (2013). Psychiatric Care in Parkinson’s Disease. Journal of Psychiatric Practice, 118-141.
Tagai, K., Nagata, T., Shinagawa, S., Tsuno, N., Ozone, M., & Nakayama, K. (Jun 2013). Mirtazapine improves visual hallucinations in parkinson’s disease: A case report. Psychogeriatrics, 13, 103-107. doi:http://dx.doi.org/10.1111/j.1479-8301.2012.00432.x
Toure JT, Brandt NJ, Limacangco MR, et al. Impact of second-generation antipsyhotics on the use of antiparkinson agents in nursing homes and assisted-living facilities. American Journal of Geriatric Pharmacotherapy. 2006; 4:25-35
Wikipedia . (2015, March). Michael J. Fox. Retrieved from Wikipedia: https://en.wikipedia.org/wiki/Michael_J._Fox