Depression in Parkinson's disease: brainstem midline alteration on transcranial sonography and magnetic resonance imaging

Abstract

Recent studies using transcranial sonography (TCS) have provided evidence of alterations in the mesencephalic midline structures in patients with unipolar depression and depression in Parkinson's disease (PD), suggesting an involvement of the basal limbic system in primary and secondary mood disorders. This study tested the hypothesis of brainstem midline abnormality in depression and investigated 31 PD patients by magnetic resonance imaging (MRI) and TCS. Signal intensity of the pontine and mesencephalic brainstem midline was rated on T2-weighted images and measured by relaxometry. In addition, two blinded investigators assessed the echogenicity of the brainstem midline by TCS. The severity of motor symptoms and depression were graded independently using standard research scales. Rating of signal intensity and T2 relaxometry of the pontomesencephalic midline structures revealed significant difference between depressed and nondepressed PD patients (P < 0.05). This corresponded to a significant reduction in mesencephalic midline echogenicity of depressed PD patients on TCS images. No correlation was found between raphe signal intensity, T2 relaxation times, or TCS echogenicity and the severity of motor symptoms or depression. This study is the first to show changes in signal intensity and T2 relaxation time of the pontomesencephalic midline structures on MRI in depressed PD patients confirming previous TCS findings. As these midline structures comprise fiber tracts and nuclei of the basal limbic system, the findings may support the hypothesis of an alteration in the basal limbic system in mood disorders.

Depression, anxiety, and apathy in Parkinson's disease: insights from neuroimaging studies

“…The other two studies applying TCS demonstrated hypoechogenicity in the brainstem raphe in dPD patients as opposed to HCs and non‐depressed PD patients 43, 48. Using DTI techniques, three out of four studies reported compromised white matter connectivity indexed by decreased fractional anisotropy (FA) in various tracts, including the bilateral anterior cingulate cortex and thalamus and multiple tracts connecting to the left frontal and deep temporal lobes 34, 35, 36.…”

Extrapyramidal symptoms and antidepressant drugs: neuropharmacological aspects of a frequent interaction in the elderly

“…On the other hand neurobiological factors have been demonstrated that support a direct involvement of brain alterations, specifically in limbic structures in the development of depressive symptoms in PD. 10,11 Akinetic-rigid forms can be observed in clinical states other than idiopathic Parkinson's disease, possibly involving other nervous structures. It is relevant to mention that parkinsonian syndromes include iatrogenic parkinsonism and the incidence of drug-induced parkinsonism is high in the elderly due to the frequent presence of multiple pathologies and consequent polypharmacotherapy.…”

Brainstem Midline Assessed by Transcranial Sonography in Parkinson's Disease: Further Evidence of a Different Etiopathogenesis of Alexithymia and Depression

“…A dynamic range of 45 dB, image brightness and time-gain compensation were adapted as needed for each examination. Echogenicity of the brainstem midline was rated in comparison with the echogenicity of the tectum of the mesencephalus and classified as grade 0=absent, 1=discontinuous, 2=continuous [8,15] ( Figure 1A example of absent raphe, Figure 1B example of continuous raphe). Grade 0 and grade 1 are classified as hypoechogenic.…”

“…Grade 0 and grade 1 are classified as hypoechogenic. Continuous echogenicity of the raphe is the normal finding in the general population [8][9][10]. Neuropsychological tests and TCS were performed and analysed in different settings and by examiners blind to diagnosis of depression/alexithymia.…”

“…Reduced echogenicity of midbrain raphe, evaluated with TCS, is a characteristic finding in depression associated with PD [7][8][9][10]. No data are available on brainstem's echogenicity in alexithymic patients.…”