# Comparison of clinical features and cerebral glucose metabolism between patients with major depressive disorder and Parkinson’s with depression

## TL;DR

This study compares depression in Parkinson’s patients and major depressive disorder patients, finding differences in symptoms and brain glucose metabolism that could help distinguish the two conditions.

## Contribution

The study identifies distinct metabolic patterns and symptom profiles in depression associated with Parkinson’s disease versus major depressive disorder.

## Key findings

- DPD patients show milder depressive symptoms but more severe cognitive impairment compared to MDD patients.
- DPD and MDD share hypometabolism in frontal, parietal, and limbic regions, but DPD has unique hypometabolism in the left posterior medial temporal lobe.
- Metabolic changes in specific brain regions may help differentiate DPD from MDD in patients with depression.

## Abstract

Whether there are differences in clinical symptoms and brain glucose metabolism between major depressive disorder (MDD) and Parkinson’s comorbid depression (DPD) is unclear. The aims of this study were to investigate the differences in characteristics in clinical and glucose metabolism between MDD and DPD and their internal correlation.

We enrolled 30 MDD patients, 25 DPD patients, and 20 Parkinson’s patients without depression (PD-ND), all of whom were evaluated by neuropsychological scales and position emission tomography (PET) imaging. We compared the differences in depressive symptoms, cognitive symptoms, and glucose metabolism imaging and analyzed metabolic characteristics and their correlation with depression.

Compared with MDD, DPD has relatively mild depressive symptoms and is dominated by general systemic symptoms. Meanwhile, the cognitive impairment of DPD is more severe, mainly in executive function. Furthermore, both DPD and MDD have extended metabolism changes in the frontal and parietal lobes and the limbic system. The FDG metabolism in the left posterior medial temporal lobe was significantly lower in patients with DPD compared to those with MDD, and this reduction was positively correlated with the severity of depressive symptoms.

MDD and DPD have some brain regions with common trends, suggesting that both of them may share a common pathophysiological basis. The specific changes, such as hypometabolism in the left primary visual cortex and right inferior lateral temporal lobe, and the hypermetabolism of the right lentiform nucleus, may contribute to the early differentiation of DPD or MDD in patients with depression.

ChiCTR2400092675 (Date of Registration: 2024-11-21).

The online version contains supplementary material available at 10.1186/s12888-025-07750-y.