Potential impact of self-perceived prodromal symptoms on the early diagnosis of Parkinson's disease.

The detection of Parkinson's disease (PD) at stages earlier than current diagnostic criteria allow for may increase the efficacy of disease-modifying therapies. Here we studied the relationship between retrospectively reported prodromal non-motor and motor features of PD, their pre-diagnostic presentation to physicians, and the extrapolated potential of an earlier diagnosis of PD considering early diagnostic markers detected at presence. One hundred and fifteen PD patients (41 women; age 63.2 ± 8.6 years) underwent a structured face-to-face interview on 22 prediagnostic symptoms. Present olfactory function, motor symptoms, and substantia nigra hyperechogenicity (SN-h) were assessed using standardized tools. Most frequently self-perceived symptoms in the early and very early prediagnostic phase (>2, >7 years prior to diagnosis) were hyposmia (23, 10 %), musculoskeletal pain (21, 9 %), and depression/anxiety (14, 11 %). In the late prediagnostic phase (≤ 2 years) mild motor signs, especially asymmetric bradykinesia and rest tremor, increasingly dominated the self-perception. In the prediagnostic phase, 99 % of patients consulted a physician because of motor symptoms but only 36 % with non-motor symptoms, mostly pain (20 %), depression/anxiety (9 %), constipation, bladder urgency, insomnia, REM sleep behaviour disorder, sexual dysfunction, and malignant melanoma (each, <6 %). Assuming the potential detectability of present hyposmia, asymmetric motor slowing and SN-h, a triad highly specific for PD, as early as 5 years prior to diagnosis, up to 84 (73 %) patients could have been identified in the prediagnostic phase using their or their physicians' awareness of early symptoms. We conclude that educating the general population and physicians on the importance of distinct prodromal features and applying symptom-specific diagnostic programs can improve the early detection of PD.