Depression and Psychosis Are Markers of More Severe Disease, Database Study Says

Mental illness in people with Parkinson’s disease, more frequently found in female and older patients, appears to associate with more severe disease, a new study reports.

Titled, “Comorbid Depression and Psychosis in Parkinson’s Disease: A Report of 62,783 Hospitalizations in the United States,” the study was published in the journal Cureus.

Although Parkinson’s disease is best known for its motor symptoms, non-motor symptoms can play an impactful role too. Depression and psychosis (difficulty discerning what’s real and what isn’t) are both psychiatric disturbances known to occur in Parkinson’s patients, and these conditions can, understandably, seriously impact their quality of life.

Researchers across the U.S. set out to examine the interplay between these mental illnesses in Parkinson’s and disease severity, patient demographics, and hospital outcomes.

They analyzed data from the Healthcare Cost and Utilization Project’s Nationwide Inpatient Sample (NIS) covering 2010–14; this included information on 62,783 people with Parkinson’s, of whom 11,358 (18.1%) were diagnosed with depression and 2,475 (3.9%) experienced psychosis.

Both mental health conditions were significantly more common in female patients; women made up 37.2% of the total population, but 44.9% of those with depression and 41.8% of those with psychosis.

Depression was more common among white patients (84.9% with depression were white, compared to 80.6% white in the total population), whereas a disproportionate percentage of people with psychosis were black (8.7% vs. 6.5% of total population) and were in the lowest quartile of household income (28.6% vs. 22.4% in the total population).

Older patients were also more likely to experience mental illness, with those older than 80 years at a 5.3-fold greater risk than patients in their 40s and 50s.

Having psychosis was associated with more severe disease: 78.8% of Parkinson’s patients with psychosis had moderate or severe disease compared to 66.2% of the total population, meaning patients with psychosis were 1.38 times more likely to have more severe disease. In those with depression, 67.9% had moderate or severe disease, a similar rate as seen in the total population.

Additionally, around a quarter of the total population received deep brain stimulation (DBS) as part of their treatment. A similar proportion of patients with depression were given DBS, but only 3.9% of patients with psychosis did.

Patients with psychosis also tended to have longer average hospital stays (7.3 vs. 4.1 days in the psychosis and total cohorts, respectively), but, interestingly, lower average total hospital charges ($31,240 vs. $39,688 in the total cohort). Both average length of hospital stay and average costs were similar for the total population and those with depression.

These results are all only associations; the study was not designed to find cause-and-effect relationships, and regardless, such relationships are likely affected by the combination of many factors. More research will be needed to better understand the interplay between these factors, but this work does highlight the impact of mental health in Parkinson’s disease.

“The results of our study suggest that healthcare providers should actively screen for psychiatric comorbidities like depression and psychosis in patients with PD [Parkinson’s disease],” the researchers concluded, adding, “[p]sychiatric comorbidities in PD should be considered an integral part of the disease, and a multidisciplinary approach to managing this disease is crucial to improve the overall outcome and the health-related quality of life of PD patients.”