Patients with newly diagnosed Parkinson’s disease and reduced CSF amyloid β1–42 may be more likely to develop Parkinson’s disease psychosis within three to four years, according to a study published in the April issue of the Journal of Neurology, Neurosurgery and Psychiatry. The type of psychotic symptom (eg, illusions or formed hallucinations) may indicate a specific profile of visual, cognitive, cortical, and hippocampal involvement in Parkinson’s disease, said the authors.
Dominic H. Ffytche, MD, PhD
“Our finding may suggest [that] early-onset Parkinson’s disease psychosis is a biomarker for the subsequent development of Alzheimer pathology,” said Dominic H. Ffytche, MD, PhD, of the Department of Old Age Psychiatry and Dementia at King’s College London.
Previous studies have indicated that visual hallucinations and illusions may be caused by specific cognitive and higher visual function deficits. Patients who develop these symptoms early in the disease course have greater rates of cognitive decline and progression to dementia, said the authors. No studies have investigated whether cognitive and higher visual function deficits are found before the onset of Parkinson’s disease, however.
Dr. Ffytche and colleagues examined the profile of cognitive, biomarker, and other risk factors before the onset of illusions and hallucinations in the Parkinson’s Progression Markers Initiative (PPMI) data set.
The PPMI is an observational multicenter study of newly diagnosed, untreated patients and healthy controls. It includes standardized, clinical, imaging, CSF, and cognitive assessments at three-month intervals during the first year and at six-month intervals in subsequent years. Assessment tools include the Montreal Cognitive Assessment, the Benton Judgement of Line Orientation, and the Unified Parkinson’s Disease Rating Scale.
Dr. Ffytche’s group included 195 healthy controls and 423 patients with Parkinson’s disease in its analysis. They compared baseline assessments in patients who developed illusions or hallucinations within three to four years of follow-up and in patients who did not develop these symptoms.
Of all patients with Parkinson’s disease, 115 people reported psychotic symptoms (predominantly illusions) at a median time of 19.5 months. At baseline, these patients had reduced CSF amyloid β1–42, lower olfaction scores, higher depression scores, and increased REM sleep behavior disorder symptoms, compared with patients without early-onset Parkinson’s disease psychosis. No differences in cognitive, higher visual, or structural imaging measures were observed, however. Dr. Ffytche and colleagues also found a subset of 21 participants with early-onset formed hallucinations who had reduced higher visual function at baseline; cortical thinning in the parietal, occipital, and frontal cortex; and reduced hippocampal volume.
One limitation of the study was its lack of phenomenologic detail about the symptoms of Parkinson’s disease psychosis. In addition, information was collected about symptoms during the week before each given assessment, thus some symptoms that occurred between assessments were missed.
—Erica Tricarico
Suggested Reading
Ffytche DH, Pereira JB, Ballard C, et al. Risk factors for early psychosis in PD: insights from the Parkinson’s Progression Markers Initiative. J Neurol Neurosurg Psychiatry. 2017;88(4):325-331.