Challenges in diagnosis of young onset Parkinson's disease
Introduction
Parkinson's disease (PD) is commonly recognized as a disease of the aged with an average onset of age 55 [1], [2]. Although overall recognized as an idiopathic disease, with respect to age of onset the categorization has been divided into early (YOPD; young-onset PD) and late (LOPD; Late/regular onset PD).
It was initially proposed that onset between 21 and 40 years of age be categorized as “young onset Parkinson's disease.” [3] Due to lack of consensus, the maximal age for young onset has varied from 40 to 55 [4], [5], [6], [7], [8], [9]. Although delineation at age 40 seems plausible [10], it has also been suggested that segregation at age 55 can produce a group similar to the 21 to 40 year group in most ways other than length of disease course [2].
YOPD patients are considered to have typical PD due to resemblance to LOPD patients in both clinical and pathological features, as well as increased incidence with age and less familial basis [8], [10]. Patients report their disease severity and disability to be largely the same, except for rate of treatment-related dyskinesias [11]. There is also debate over whether differences exist between both groups in manifestation of psychiatric disorders [12].
Despite the similarities, we suspect that PD is often not considered in the differential diagnosis for YOPD patients since PD classically has later onset. Physicians' lack of consideration of or strong reluctance towards diagnosing younger patients with PD may lead to significant delays in diagnoses. This may also result in extensive occupation of medical resources, including increased number of medical investigations and visits to the same or multiple neurologists prior to final diagnosis. In order to assess the diagnosis timeline of YOPD patients, we analyzed history prior to diagnosis in a sample of 337 PD patients. For comparison purposes each YOPD patient was matched to a LOPD patient on the basis of gender, tremor presence, and stage of PD.
Section snippets
Patient source
All individuals in the study were diagnosed with idiopathic PD and regularly followed in a community-based PD and movement disorders center from 2005 to 2011. The criteria used to make PD diagnosis were based on the UK Parkinson's Disease Society Brain Bank clinical diagnostic criteria [13]. We excluded patients with atypical parkinsonism for consistency. This narrowed the sample of patients to 337 subjects.
The method of this study conforms to the provisions of the Declaration of Helsinki in
Results
Of the 337 patients identified to have PD, 14 individuals (4.2%) were YOPD patients. The patients were split evenly by gender and all were at Hoehn and Yahr stage 2 when diagnosed. Tremor was present in 9 patients. Due to matching, the LOPD patient group was identical in these aspects. The YOPD and LOPD groups had five and one individuals, respectively, which were given functional diagnoses prior to reaching final diagnosis of idiopathic PD.
Statistical analysis for comparison of means of scalar
Discussion
Certainly, a factor in the diagnostic challenge of YOPD is its rarity. Even neurologists who make such consideration may give preference to other diagnoses due simply to the age of patients. The 4.2% prevalence rate seen in our study was within the estimated 3% to 5% of all PD patients who may be classified as YOPD [10].
The notion that age is a predominant consideration for PD diagnosis is evident in the results showing that a difference in means of over 15 months is observed between YOPD and
Conclusions
Although YOPD and LOPD are substantially similar in symptomatology, clinicians often require more time to conclusively diagnose YOPD patients due to perceiving PD as a disease of the aged. The resulting negative impact on patients and clinical resources, in this study, is partially exemplified by the increased number of visits to one or multiple neurologists and number of investigations prior to diagnosis.
Financial disclosure and conflict of interest
There are no financial disclosures and conflicts of interest as the research was performed on a voluntary basis.
Acknowledgment
We acknowledge Ambreen Nadeem for her help in data collection and formatting of this study.
References (24)
- et al.
Epidemiological, clinical, and genetic characteristics of early-onset parkinsonism
Lancet Neurol
(2006) - et al.
Frequency of psychiatric disorders in young-onset Parkinson's disease does not differ from typical-onset Parkinson's disease
Parkinsonism Relat Disord
(2009) - et al.
Young onset Parkinson's disease. Practical management of medical issues
Parkinsonism Relat Disord
(2008) - et al.
Impact of Parkinson's disease on patients' adolescent and adult children
Parkinsonism Relat Disord
(2004) - et al.
Psychosocial issues in young-onset Parkinson's disease: current research and challenges
Parkinsonism Relat Disord
(2008) - et al.
Heterogeneity of Parkinson's disease in the early clinical stages using a data driven approach
J Neurol Neurosurg Psychiatry
(2005) - et al.
A clinico-pathological study of subtypes in Parkinson's disease
Brain
(2009) - et al.
Young onset Parkinson's disease
Mov Disord
(1987) - et al.
Clinical course in Parkinson's disease: relationship to age at onset
J Neurol
(1985) - et al.
A comparison of clinical and pathological features of young- and old-onset Parkinson's disease
Neurology
(1988)