Psychosis in Parkinson’s disease (PD) is common and associated with a range of negative outcomes. Dementia and psychosis are highly correlated in PD, but the frequency and correlates of psychosis in patients without cognitive impairment are not well understood. One hundred and ninety-one non-demented PD patients at two movement disorders centers participated in a study of neuropsychiatric complications in PD and completed a detailed neurological and neuropsychiatric assessment, including the rater-administered Parkinson Psychosis Rating Scale for hallucinations, delusions, and minor symptoms of psychosis (illusions and misidentification of persons). Psychotic symptoms were present in 21.5% of the sample. Visual hallucinations were most common (13.6%), followed by auditory hallucinations (6.8%), illusions or misidentification of people (7.3%), and paranoid ideation (4.7%). Visual hallucinations and illusions or misidentification of people were the most common comorbid symptoms (3.1%). Depression (P = 0.01) and rapid eye movement behavior disorder symptoms (P = 0.03) were associated with psychosis in a multivariable model. The odds of experiencing psychotic symptoms were approximately five times higher in patients with comorbid disorders of depression and sleep-wakefulness. Even in patients without global cognitive impairment, psychosis in PD is common and most highly correlated with other non-motor symptoms. Screening for psychosis should occur at all stages of PD as part of a broad non-motor assessment. In addition, these findings suggest a common neural substrate for disturbances of perception, mood, sleep-wakefulness, and incipient cognitive decline in PD.

While the Research Domain Criteria (RDoC) acknowledges that environmental and developmental influences represent important elements of the RDoC framework, there is little specificity regarding how and when to systematically examine the impact of these dimensions on domains of function. The primary aims of this paper are to demonstrate the ways in which the RDoC can be expanded to include an explicit emphasis on (a) assessing within-individual change in developmental processes over time and (b) evaluating the extent to which selective and measurable environmental influences drive meaningful change during key developmental periods. We provide data from an ongoing randomized control trial as a proof of concept to highlight how repeated assessments within an experimental intervention design affords the unique opportunity to test the impact of environmental influences on within-individual change. Using preliminary data from 77 mother–child dyads repeatedly assessed across 12 months during the sensitive preschool period, we demonstrate the impact of change in maternal emotion regulation (ER) on within-individual growth in child ER and link that growth to fewer teacher-reported externalizing problems. In line with this Special Issue, findings are discussed within the context of expanding and clarifying the existing RDoC framework to explicitly incorporate environmental and developmental dimensions.

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