Annotated Abstracts of Journal Articles
2015, 2nd Quarter
Annotations by Nicholas Kontos, MD
Also of interest:
ANNOTATION (Nicholas Kontos)
The Finding: A history of an inpatient or specialist diagnosis of “depression” was associated with an increased risk of Parkinson’s disease onset. This relationship was stronger with more recent depressive illness (OR 3.21 for patients with depression within one year of enrolment) but remained significant at 25 years out (OR 1.47). Severity of depression (proxy measures included hospitalization, recurrence, and treatment-refractoriness) also correlated significantly with risk of eventual Parkinson’s disease onset.
Strengths and Weaknesses: A Scandinavian study (Sweden), the authors drew upon a massive national database to obtain a final study cohort of over 140,000. 25 years of data were available. Psychiatric comorbidities were not considered, but the authors felt that, if anything, this omission was more likely to dilute their findings than inflate them. While they did not specifically designate the “depression” cases as having major depressive disorder, the diagnostic integrity of the depressive (and Parkinson’s) patients is supported by all diagnoses having been made by specialists.
Relevance: The association between Parkinson’s disease and depression is usually discussed in terms of the former preceding the latter. This paper summarizes and substantially adds to a literature indicating that the opposite sequence also exists. This might be useful in the future in terms of Parkinson’s surveillance and in terms of getting at pathophysiologic underpinnings of both conditions.
Objective: To investigate the long-term risk of Parkinson disease (PD) after depression and evaluate potential confounding by shared susceptibility to the 2 diagnoses.
Methods: The nationwide study cohort included 140,688 cases of depression, matched 1:3 using a nested case-control design to evaluate temporal aspects of study parameters (total, n = 562,631). Potential familial coaggregation of the 2 diagnoses was investigated in a subcohort of 540,811 sibling pairs. Associations were investigated using multivariable adjusted statistical models.
Results: During a median follow-up period of 6.8 (range, 0-26.0) years, 3,260 individuals in the cohort were diagnosed with PD. The multivariable adjusted odds ratio (OR) for PD was 3.2 (95% confidence interval [CI], 2.5-4.1) within the first year of depression, decreasing to 1.5 (95% CI, 1.1-2.0) after 15 to 25 years. Among participants with depression, recurrent hospitalization was an independent risk factor for PD (OR, 1.4; 95% CI, 1.1-1.9 for ≥5 vs 1 hospitalization). In family analyses, siblings’ depression was not significantly associated with PD risk in index persons (OR, 1.1; 95% CI, 0.9-1.4).
Conclusions: The time-dependent effect, dose-response pattern for recurrent depression, and lack of evidence for coaggregation among siblings all indicate a direct association between depression and subsequent PD. Given that the association was significant for a follow-up period of more than 2 decades, depression may be a very early prodromal symptom of PD, or a causal risk factor.
ANNOTATION (Nicholas Kontos)
The Finding: Emotional distress, but not psychopathology per se, was significantly associated with frequency and severity of motor blocks and festination in Parkinson’s disease. This included association with falls and impaired functioning.
Strengths and Weaknesses: Psychiatric diagnoses were made using structured, well-established instruments administered by clinical psychologists or research nurses “blind to neurological findings,” This blindness is hard to imagine given the observable pathology inherent to Parkinson’s disease. The authors attempted to develop a Motor Blocks and Festination Scale, which assessed not only these Parkinsonian symptoms, but also the presence or absence of “emotional distress” concomitant with them. Obviously, as the authors state, their scale will require further use and validation before we can be fully comfortable with results obtained through its use.
Relevance: Psychosomatic medicine specialists are fond of pointing out relationships between “stress” and manifestations of illness, and they are expected to know about them. This study is particularly interesting in its discrimination between psychiatric diagnoses and (presumably) non-pathological “emotional distress.” Finding the latter but not the former to be associated with motor blocks and festination opens up new possibilities for inquiry and intervention (stress identification and reduction training) for helping patients with Parkinson’s disease.
Recent studies suggest that depression and anxiety in patients with Parkinson’s disease may predispose them to freezing. Although festination is also frequent, the association with emotional disorders has not been examined. The aim of the authors was to clarify the association between freezing and festination with anxiety, depressive disorders, and emotional distress. The authors examined a consecutive series of 95 patients with Parkinson’s disease using comprehensive psychiatric assessments and a new instrument specifically designed to assess the severity of freezing, festination, and emotional distress (Motor Blocks and Festination Scale). All patients were assessed with the Motor Blocks and Festination Scale, the Mini International Neuropsychiatric Interview, and scales to measure the severity of mood and anxiety disorders. A linear regression analysis showed that both motor blocks and festination were significantly associated with emotional distress and deficits on activities of daily living. Conversely, there was no significant association between motor blocks or festination and generalized anxiety disorder, panic disorder, agoraphobia, social phobia, or depression. Motor blocks and festination are significantly associated with emotional distress, but no significant associations were found with anxiety or affective disorders.