Depression May Be an Early Manifestation of Neurodegenerative Changes Leading to Movement Disorders

Findings from a study published in General Psychiatry suggest that depression may lead to the onset of Lewy body dementia and Parkinson disease. Specifically, the researchers observed that the neurodegenerative changes from incident depression were present and said that depression—particularly at a later age—should raise awareness of potential Lewy body dementia and Parkinson disease.¹

What Are Lewy Body Dementia and Parkinson Disease?

Lewy body dementia is the second most common type of dementia after Alzheimer disease, according to Mayo Clinic. Protein deposits called Lewy bodies develop in the nerve cells in the brain and affect regions that are involved in thinking, memory, and movement. This decline gradually worsens over time, and in some patients, may cause visual hallucinations and changes in alertness or attention. Dementia with Lewy bodies and Parkinson disease dementia are the 2 forms of Lewy body dementia that cause cognitive symptoms.²

Parkinson disease is a movement disorder of the nervous system that worsens over time. Symptoms begin slowly and are often barely noticeable, such as a tremor in one of the hands or feet or in the jaw. Although tremors are common, patients with Parkinson disease can also experience slowing movement, trouble with balance resulting in falls, and stiffness. Additionally, in early stages, patients’ faces may show little or no expression, the arms may not swing when walking, and speech can become soft or slurred.³

Symptoms are similar across the 2 conditions, and can include the following: slowed movement (bradykinesia); rigid muscles; loss of movement; speech changes; and nonmotor symptoms, including depression, anxiety, and sleep problems.^2,3 Additionally, depression is a common comorbidity of both Lewy body dementia and Parkinson disease, with it being present in an estimated 35% and 50% cases, respectively.^4,5

Quantifying the Incidence of Depression Preceding and Following the Diagnosis of Lewy Body Dementia and Parkinson Disease

To study the incidence of depression before or following the diagnosis of these conditions, the investigators conducted a retrospective case-control study using Danish registers to identify all patients with a diagnosis of either Lewy body dementia or Parkinson disease from 2007 to 2019. These patients were matched by age, calendar year of diagnosis, and sex with up to 3 patients diagnosed with rheumatoid arthritis (RA), chronic kidney disease (CKD), or osteoporosis, respectively.¹

The outcome was incident depression, and this was assessed for up to 10 years before and after the diagnosis of either Lewy body dementia or Parkinson disease. Hazard rates of incident depression for patients, both before and after diagnosis, were compared with those for patients with RA, CKD, or osteoporosis using a Cox-proportional hazards model.¹

The investigators identified 17,711 patients with Lewy body dementia or Parkinson disease (median age: 74.98 years [68.10–80.85]; female: 39.92%) who were matched to 19,556, 40,842, and 47,809 patients with RA, CKD, and osteoporosis, respectively. In the 10 years preceding diagnosis, 520 (16.91%) patients with Lewy body dementia and 1918 (13.10%) patients with Parkinson disease experienced incident depression (median prediagnostic observation time: 6.7 years [3.8–9.3 years]). For comparison, 1087 (5.56%), 3192 (7.82%), and 3460 (7.24%) patients with RA (median prediagnostic observation time: 6.4 years [3.7–9.2]), CKD (median prediagnostic observation time: 7.0 years [4.2–9.6]), and osteoporosis (median prediagnostic observation time: 6.9 years [4.1–9.6]) experienced incident depression in the 10-year prediagnostic period. For those with Lewy body dementia, Parkinson disease, RA, CKD, and osteoporosis who developed depression, respectively, 100 (19.23%), 362 (18.87%), 191 (17.57%), 490 (15.35%), and 519 (15.00%) had a prediagnostic psychiatric hospital contact that led to a diagnosis of depression.¹

In the 10 years following diagnosis, 261 (8.49%) patients with Lewy body dementia and 1160 (7.93%) patients with Parkinson disease experienced incident depression (median postdiagnostic observation time: 3.1 years [1.3–5.7]). For comparison, 992 (5.07%), 2240 (5.48%), and 2911 (6.09%) patients with RA (median postdiagnostic observation time: 4.7 years [2.3–7.7]), CKD (median postdiagnostic observation time: 2.6 years [0.8–5.1]), and osteoporosis (median postdiagnostic observation time: 3.8 years [1.7–6.6]) experienced incident depression in the 10-year postdiagnostic period. Additionally, for those with Lewy body dementia, Parkinson disease, RA, CKD, and osteoporosis who developed depression, respectively, 45 (17.24%), 241 (20.78%), 170 (17.14%), 344 (15.36%), and 519 (17.83%) had a postdiagnostic psychiatric hospital contact that led to a depression diagnosis.¹

"Following a diagnosis of [Parkinson disease] or [Lewy body dementia], the persistent higher incidence of depression highlights the need for heightened clinical awareness and systematic screening for depressive symptoms in these patients,” first author Christopher Rohde, MD, PhD, Department of Affective Disorders at Aarhus University Hospital – Psychiatry in Aarhus, Denmark, said in a news release. "Thus, our main conclusion—that [Lewy body dementia and Parkinson disease] are associated with a marked excess depression risk preceding and following diagnosis when compared with other chronic conditions—remains valid."⁶

REFERENCES

1. Rohde C, Langeskov-Christensen M, Jørgensen LB, Borghammer P, Østergaard SD. Depression preceding and following the diagnosis of Parkinson's disease and Lewy body dementia. Gen Psychiatr. 2025;38(6):e102405. doi:10.1136/gpsych-2025-102405

2. Mayo Clinic. Lewy body dementia. Accessed January 21, 2026. https://www.mayoclinic.org/diseases-conditions/lewy-body-dementia/symptoms-causes/syc-20352025

3. Mayo Clinic. Parkinson’s disease. Accessed January 21, 2026. https://www.mayoclinic.org/diseases-conditions/parkinsons-disease/symptoms-causes/syc-20376055

4. Jellinger KA. Depression in dementia with Lewy bodies: a critical update. J Neural Transm (Vienna). 2023;130(10):1207-1218. doi:10.1007/s00702-023-02669-8

5. Parkinson’s Foundation. Depression. Accessed January 21, 2026. https://www.parkinson.org/understanding-parkinsons/non-movement-symptoms/depression

6. Shanghai Jiao Tong University Journal Center. Depression may be an early warning sign of Parkinson’s disease and Lewy body dementia. News release. January 13, 2026. Accessed January 21, 2026. https://www.eurekalert.org/news-releases/1112417