Neuropsychiatric symptoms variable in early Parkinson’s disease

By Eleanor McDermid, Senior medwireNews Reporter

The prevalence of neuropsychiatric symptoms is increased in patients with early Parkinson’s disease (PD), although many remain stable over time, shows follow-up of the Parkinson’s Progression Markers Initiative (PPMI).

The analysis also confirms that patients may develop new neuropsychiatric symptoms when they start dopamine replacement therapy (DRT).

The 423 patients who completed baseline assessments had significantly higher rates of depression, fatigue, apathy and psychosis than 196 healthy controls, and had higher scores for anxiety.

Among the 96 patients who completed 2 years of follow-up, rates of apathy rose significantly, from 16.7% to 30.2%, as did psychosis rates, from 3.0% to 10.0%. There was a trend towards an increase in fatigue, but other symptoms remained stable or increased only slightly over time.

By the 2-year follow-up, 81.1% of patients had started treatment. As anticipated, DRT, in 42 patients, resulted in an increased incidence of some neuropsychiatric symptoms. There were six new cases of impulse control disorders, all among patients who had been taking DRT for at least 1 year, compared with none in untreated patients, and the incidences of excessive daytime sleepiness were 31.0% versus 10.6%. Also, the rate of new-onset psychosis was about threefold higher in treated than untreated patients, although this was not statistically significant.

By contrast, fatigue improved on starting DRT, with 33.3% of treated patients who were fatigued experiencing significant improvements, compared with 11.1% of untreated patients.

The study authors, led by Patricia de la Riva (University Hospital Donostia, San Sebastián, Spain), note that although up to 25% of the PD patients were taking antidepressants during the study, around two-thirds of the 19% of patients who screened positive for depression at any given follow-up were not receiving treatment.

“Since depression symptoms did worsen over time in this study and have been shown to influence the initiation of DRT in a previous study, it is important to appropriately screen for and adequately treat depression in this population starting at disease onset”, the team writes in Neurology.

Cognitive performance worsened slightly in the patients over time, but by no more than in the controls. However, a third of the patients who were cognitively impaired at the baseline screening were classed as cognitively normal at a later assessment. The rate of depression was similarly variable during follow-up.

“These findings highlight the limitations of performing single time point assessments and using screening instruments instead of more detailed diagnostic or assessment tools”, say the researchers.

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