The Very Real and Deep Depression of Parkinson's Disease

Those with Parkinson’s often suffer from debilitating depression, anxiety, and personality disorders. Extreme unhappiness and despair in those with Parkinson’s are twice that experienced in other disabling diseases. Depression symptoms do not follow the same slow progression as the physical symptoms of Parkinson's. The depression suffered by Parkinson’s patients is independent, but at the same time connected to their physical deterioration.

Depression among those with Parkinson’s disease is problematic to diagnose. There are no consistent assessment implements planned to gage the symptoms of depression in connection with Parkinson’s, and the relationship between this disease and anxiety plus depression is not very well understood. What is known as a general degeneration of the neurotransmitter system plays a role in the occurrence of those with depression and Parkinson’s disease.

To test the theory researchers used [11C} RTI-32 PET, an in vivo marker of dopamine and noradrenaline transporting binding to determine the differences between those who were depressed and those who were not affected by depression in Parkinson's. To simplify the scientific language, PET is positron emission tomography or a nuclear imaging technique that allows testing to be done on isolated cells rather than on an entire organism. In other words, cultured cells biopsied from living tissue. PET imaging is an excellent tool used to assess the underlying causes of Parkinson’s disease; the study also evaluated the complications and management of Parkinson’s. If researchers can find the find the money to use this neuroimaging technology regularly, great strides will result in the study of this disease.

What is Parkinson’s disease?

A neurodegenerative disorder characterized by tremors, rigidity, and bradykinesia is the description of Parkinson’s disease. The causes are associated with the loss or death of dopaminergic neurons (DA) in the substantia nigra pars compacta (the mid-brain). Dopamine neurons do not directly control movement but have an indirect role in regulating the striatum that contributes to fine motor control, or the part of the brain that controls movement. 

The degeneration of neurons in the substantia nigra pars compacta or mid-brain is the principal problem that underlies Parkinson’s disease.  Studies also show that pathological changes to the dopaminergic neurons of the midbrain are also involved in schizophrenia, dementia and other mental disorders.

Researchers studied eight and then 12 Parkinson’s disease patients. The regions studied included the "caudate, putamen, substantia nigra, thalamus, amygdala, anterior cingulate cortex (CingA, Brodmann areas 24–32), orbitofrontal cortex (OF, areas 11/47) and dorsolateral prefrontal cortex (DLPF, areas 10/45/46)." These regions were chosen because they receive abundant monoaminergic projections or because of their implication in depression (Drevets, 1998.) Some participants had a history of depression, and some did not, but all were matched for age, length of time with Parkinson’s disease, and their doses of antiparkinsonian medication. Those who were both depressed and suffered from Parkinson’s disease had lower [11C] RTI-3 binding in the locus coeruleus than those Parkinson’s patients who were not depressed.  The locus coeruleus is the nucleus in the pons of the brainstem that is involved with psychological responses to stress and panic. (The pons is part of the brainstem).

Read on to learn more about what this study has found about depression and Parkinson's disease.