Depression Increases Risk of Parkinson Disease, Dementia, and Mortality, Study Finds

Depression in Parkinson disease (PD) is not just a consequence of motor symptoms but may be an early indicator of the disease, associated with increased mortality and dementia risk, according to a study published in the Journal of Neurology, Neurosurgery, & Psychiatry.

“We identified a nested cohort of participants with PD, and hypothesized that within this cohort; depression would be associated with reduced regional brain volumes; become increasingly common in the years prior to PD diagnosis; that depression would be associated with greater intensity and extent of neurodegenerative change as indexed by regional brain volumes; that depression would signal increased risk of dementia and death among those with PD,” explained James Badenoch, Centre for Preventive Neurology, Queen Mary University of London, London, UK, and Department of Neuroimaging, King's College London Institute of Psychiatry Psychology & Neuroscience, London, UK, and coauthors.

The researchers analyzed data from over 2600 individuals with PD. Results showed that individuals diagnosed with depression were 1.53 times more likely to develop PD, even after adjusting for factors like age, sex, and socioeconomic status. The analysis also found that depression became more common as PD diagnosis approached and continued to increase afterward. Importantly, individuals with severe depressive symptoms had twice the risk (2.04 times) of developing PD compared to those without depression.

Neuroimaging data revealed that depression in PD patients was linked to reduced grey matter volume in 18 brain regions, including the thalamus and amygdala, which are critical for emotion and motivation regulation. This reduction in brain volume highlights the structural impact of depression in PD, offering further insight into its biological underpinnings.

The study also demonstrated that depression diagnosed prior to PD was associated with a 40% increased risk of all-cause mortality, particularly in those who developed depression within three years before PD onset. Furthermore, depression before PD diagnosis raised the risk of subsequent dementia by 49%, underscoring the importance of early detection and treatment of depression in patients at risk for or diagnosed with PD.

“Depression in PD is associated with poorer prognosis and neurodegeneration; this has clinical implications in stratifying people with poorer cognitive and prognostic trajectory in PD,” concluded the study authors.

Reference

Badenoch JB, Paris A, Jacobs BM, Noyce AJ, Marshall CR, Waters S. Neuroanatomical and prognostic associations of depression in Parkinson's disease. J Neurol Neurosurg Psychiatry. 2024;95(10):966-973. doi:10.1136/jnnp-2023-333007