Atrophy in Thalamus Linked to More Severe Non-motor Problems in Parkinson’s Patients

Atrophy in Thalamus Linked to More Severe Non-motor Problems in Parkinson’s Patients
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People with severe non-motor symptoms related to Parkinson’s disease (PD) have a smaller thalamus compared to those with similar but mild to moderate symptoms, a brain imaging study suggests.

Sleeping and gastrointestinal problems are also tied to atrophy (shrinking) of the thalamus, a part of the inner brain known to process motor signals and to regulate consciousness, alertness, and sleep.

The study, “Sleep disturbances and gastrointestinal dysfunction are associated with thalamic atrophy in Parkinson’s disease,” was published in the journal BMC Neuroscience

Parkinson’s is marked by a progressive loss of coordination and movement. In addition to difficulties in movement (motor symptoms), it can cause a variety of non-motor symptoms such as sleep problems, depression, gastrointestinal and urinary problems, and difficulty thinking (cognitive impairment).

Techniques such as magnetic resonance imaging (MRI) help to diagnose PD through brain scans, and they can also help identify structural changes in the brain — like changes in thickness or volume — associated with its non-motor symptoms.

But the exact location of specific brain areas linked to non-motor symptoms is still unclear. 

Researchers recruited 41 patients diagnosed with idiopathic (unknown origin) PD at the Movement Disorders clinics at King’s College Hospital in London. All were analyzed through MRI brain scans.

None of these patients chosen showed signs of mild PD cognitive impairments or disease-related dementia, and they had no history of neurological or psychiatric disorders.

Patients were first assessed by medical staff using the Non-motor Symptoms Scale for PD (NMSS), then self-assessed using the Non-motor Symptoms Questionnaire (NMSQ). The Beck Depression Inventory-II (BDI-II) and the Hamilton Depression Rating Scale (HDRS) evaluated neuropsychiatric symptoms.

Motor symptoms stages were determined with the Hoehn & Yahr (H&Y) scale, general cognitive status was assessed using the Mini Mental Status Examination (MMSE), and quality of life (QoL) was measured by patients completing the 39-item PD Questionnaire (PDQ-39).

All were required to stop taking dopamine-related medications the night before the scans to avoid involuntary movements caused by side effects. 

Patients were then divided into two groups based on their NMSS scores. A total of 23 patients who scored 40 or below were considered to have mild to moderate non-motor Parkinson’s symptoms, while 18 who scored 41 or above were defined as severe. 

Results showed that, compared to those with mild to moderate symptoms, those with severe non-motor symptoms were older, had the disease longer, were using higher doses of medication, had higher H&Y scores, and reported a lower QoL. Severe non-motor PD patients also scored more poorly in the sleep and fatigue sections of the NMSS. 

MRI scans were taken, and the cortical (outer brain) thickness and subcortical (inner brain) volumes were calculated and compared with patient assessments.

Analyses revealed that the inner brain’s thalamus was significantly smaller in volume (thalamic atrophy) in PD patients with severe non-motor symptoms, compared to those with mild to moderate symptoms. 

Other areas of the inner brain, including the hippocampus, the amygdala, were similar between the two groups. No differences in the thickness of the outer brain were seen. 

Researchers then divided patients into two groups based on sleep/fatigue problems and gastrointestinal tract dysfunction. Compared to those without these problems, a smaller thalamus was significantly associated with sleep and gastrointestinal disturbances. 

“This is the first study showing an association between higher non-motor symptom burden and thalamic atrophy in PD. Among the non-motor symptoms, sleep/fatigue disturbances and gastrointestinal dysfunction were the non-motor symptoms that drove this correlation,” the researchers wrote.

The team, however, noted that further studies with larger numbers of PD patients are needed to confirm these findings, and use specific scales to measure nighttime and daytime sleep problems and tools that capture gastrointestinal dysfunction.

Steve holds a PhD in Biochemistry from the Faculty of Medicine at the University of Toronto, Canada. He worked as a medical scientist for 18 years, within both industry and academia, where his research focused on the discovery of new medicines to treat inflammatory disorders and infectious diseases. Steve recently stepped away from the lab and into science communications, where he’s helping make medical science information more accessible for everyone.
Total Posts: 13
Patrícia holds her PhD in Medical Microbiology and Infectious Diseases from the Leiden University Medical Center in Leiden, The Netherlands. She has studied Applied Biology at Universidade do Minho and was a postdoctoral research fellow at Instituto de Medicina Molecular in Lisbon, Portugal. Her work has been focused on molecular genetic traits of infectious agents such as viruses and parasites.
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Steve holds a PhD in Biochemistry from the Faculty of Medicine at the University of Toronto, Canada. He worked as a medical scientist for 18 years, within both industry and academia, where his research focused on the discovery of new medicines to treat inflammatory disorders and infectious diseases. Steve recently stepped away from the lab and into science communications, where he’s helping make medical science information more accessible for everyone.
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