Parkinsonism is the generic name given to a group of conditions; a clinical syndrome comprising combinations of motor problems – such as tremor, bradykinesia, resting tremor, rigidity, flexed posture and loss of postural reflexes. Although the vast majority of people with Parkinsonism have Parkinson’s disease (PD), there are other, less common, causes of Parkinsonism – namely, Multiple System Atrophy (MSA), Progressive Supranuclear Palsy (PSP), Corticobasal Degeneration (CBD) and Dementia with Lewy bodies (DLB). These other neurodegenerative conditions are sometimes grouped together under the term of “atypical parkinsonism” or “parkinson-plus syndromes”. Parkinsonism can also be symptomatic (i.e. arising from another cause), as a result of various vascular, drug-related, infectious, toxic and other known secondary causes. Of these, drug-induced Parkinsonism is probably the most common.
Parkinsonian disorders affect both sexes equally, with PSP being marginally more prevalent among males, and are most commonly seen in the middle-aged to elderly population. Due to clinical challenges in diagnosis between the disorders, as well as the Parkinsonism affecting the middle aged to elderly, actual incidence (the rate of new diagnosed cases) and prevalence (the actual number of cases living with disease) are challenging to retain.
The most common Parkinsonian disorder is PD with a prevalence rate of approximately 4% by the age of 80 years, which represents around 80% of all individuals with Parkinsonism. The incidence rate for the PSP, MSA, and CBD is estimated at just below one case per 100,000. DLB is a more frequent occurrence and about 3-4 new cases being diagnosed per year in the general population.
Pathogenesis & Clinical Features
The clinical syndrome Parkinsonism, as seen in PD and atypical Parkinsonism, is mainly distinguished by tremor, rigidity of muscles, mobility problems and bradykinesia. This symptomatology is shared between both typical and atypical PD. What distinguishes atypical parkinsonian disorders from typical PD is generally a more rapidly progressive Parkinsonism associated with early postural instability, poor response to dopaminergic therapy, such as L-DOPA, and additional symptoms such as supranuclear gaze palsy, early autonomic failure, pyramidal signs, cerebellar features and alien limb or apraxia.
Current Therapies/Future Aims
Right now the initial treatment offered to an individual newly diagnosed with Parkinsonism is dopamine replacement therapy. If the case is unresponsive PD is generally excluded. For atypical parkinsonian disorders, no pharmacological treatment has been shown beneficial except for MSA that in some cases has a slight beneficial impact. Most current therapies used to help managing atypical parkinsonian disorders are non-pharmacological, such as – physical and occupational therapy. Blood pressure medication is in sometimes helps with autonomic dysfunctions that MSA cases may suffer from. All available therapeutical strategies, including dopamine replacement therapy and deep brain stimulation in the case of PD, are all symptomatic strategies and there are no current strategies to prevent disease and no cure is available.
The future aims when dealing with these neurological disorders are finding ways to better and more efficiently diagnose and distinguish between this spectrum of disorders, in order to understand what sets them apart and what commonalities they share to which we could target therapeutical aims. New drugs are being developed which target tau protein aggregation, which if successful could have a great impact on people suffering from Parkinsonism. A lot of research focus is directed towards understanding the molecular etiology from, both by finding genes implicated as well as how dysfunction in their related proteins leads to the pathogenesis seen. Finding cellular mechanisms and risk factors to disease will ultimately lead to a targeted development of therapeutical strategies.