Biological Features

PD is associated with a range of biological features observable via histological and biochemical examination of tissue, brain imaging, and in vivo electrophysiological recordings.

Micrograph of brain cells containing a Lewy bodyImage by Kondi Wong, Armed Forces Institute of PathologyAt present, conclusive diagnosis of PD requires post mortem examination of neural tissue that identifies characteristic histopathological features, including Lewy bodies. Neuron loss and gliosis (spongiosis) is observed, as well as neuronal lesions. These lesions can include a number of proteins and protein structures, though the relationship between these structures and pathology of the disease remains unclear. Some proteins associated with PD and related neurodegenerative diseases include:

• Alpha-synuclein, a major constituent of Lewy bodies, which are defining features of PD
• Tau, which forms neurofibrillary tangles and Pick bodies
• Ubiquitin, also found in Motor Neuron Disease Inclusions (MND-I)

Glial lesions are also observed in PD, and can be composed of tau, found in coiled bodies and tufted astrocytes or astrocytic plaques, and/or alpha-synuclein, observed in glial cytoplasmic inclusions.