Depressive symptoms in Parkinson’s disease

[Anxiogenic and depressogenic side-effects of non-psychiatric drugs]

Although medications such as anticancer, antimicrobial, immunomodulatory, neurological or hormonal therapies may have a negative impact on mood, adequate attention was not paid until the withdrawal of rimonabant in 2008. In the present study the authors review full spectrum of currently available medications discussing anxiety and depression as possible adverse effects of treatment. A relatively high risk of depression should always be considered when pharmacotherapy applied, especially if current depressive episodes, positive family history, or neurotic personality traits increasing susceptibility to depressogenic effects. Prior to start of medical treatment, the potential effectiveness of the given drug should be precisely evaluated, and alternative medical and non-medical treatment options should also be carefully considered. In addition, monitoring patients during treatment for signs of depressive or anxious symptoms is necessary.

[The Parkinson puzzle]

Parkinson's disease is one of the most frequent progressive degenerative disorders with unknown origin of the nervous system. The commutation of the disease on Guam led to the discovery of a neurotoxin which was also found in other continents. This neurotoxin was identified in the common cyanobacteria (blue-green algae). Early clinical observations suggested some loose correlations with gastric and duodenal ulcer and Parkinson's disease, while recent studies revealed a toxin, almost identical to that found in cyanobacteria in one strain of Helicobacter pylori, which proved to cause Parkinson like symptoms in animals. Therefore, it cannot be ruled out that there is a slowly progressive poisoning in Parkinson's disease. The disease specific alpha-sinuclein inclusions can be found in nerve cells of the intestinal mucosa far before the appearance of clinical symptoms indicating that the disease may start in the intestines. These results are strengthened by the results of Borody's fecal transplants, after which in Parkinson patients showed a symptomatic improvement. Based on these observations the Parkinson puzzle is getting complete. Although these observations are not evidence based, they may indicate a new way for basic clinical research, as well as a new way of thinking for clinicians. These new observations in psycho-neuro-immunology strengthen the fact that immunological factors may also play a critical factor facilitating local cell necrosis which may be influenced easily.

Emotional blunting following left basal ganglia stroke: the role of depression and fronto-limbic functional alterations

Disorders of the basal ganglia (BG) alter perception and experience of emotions. Left hemisphere BG (LBG) stroke is also associated with depression. The interplay between depression and alterations in emotional processing following LBG stroke was examined. Evoked affective responses to emotion-laden pictorial stimuli were compared among LBG stroke and healthy participants and participants with stroke damage in brain regions not including the LBG selected to equate depression severity (measured using the Hamilton Depression Scale) with LBG damage participants. Brain activity {[O(15)]water positron emission tomography, PET} was measured in LBG stroke relative to healthy participants to identify changes in regions associated with emotion processing and depression. LBG stroke subjects reported less intense emotions compared with healthy, but not stroke comparison participants. Depression negatively correlated with emotional experience for positive and negative emotions. In response to positive stimuli, LBG subjects exhibited higher activity in amygdala, anterior cingulate, dorsal prefrontal cortex, and insula compared to healthy volunteers. In response to negative stimuli, LBG subjects demonstrated lower activity in right frontal-polar region and fusiform gyrus. Higher baseline activity in amygdala and ventral and mesial prefrontal cortex and lower activity in left dorsal lateral prefrontal cortex were associated with higher depression scores. LBG stroke led to blunted emotions, and brain activity alterations accounting for reduced affective experience, awareness and depression. Depression and fronto-limbic activity changes may contribute to emotional blunting following LBG stroke.

Hedonic tone and its mood and cognitive correlates in Parkinson's disease

BACKGROUND

Anhedonia has been mainly reported as a symptom of depression and cognitive impairment in Parkinson's disease (PD) patients. Here, we investigated whether hedonic tone depends on depression and clarified its relationship with the cognitive performance of PD patients with different mood disorders.

METHODS

In 254 patients, we assessed hedonic tone using the Snaith-Hamilton Pleasure Scale, depression severity using the Beck Depression Inventory, and cognitive performances using the Mental Deterioration Battery. A structural psychiatric interview was used to diagnose major depressive disorder (MDD) and minor depressive disorder (MIND), according to the DSM-IV-TR criteria.

RESULTS

PD patients with diagnosis of MDD were more anhedonic than those with MIND and those without depressive disorders. Reduced hedonic tone correlated with depression severity in patients with MDD and no depressive disorders. In multivariate models that consider depression severity and cognitive performances together, anhedonia was related to increased depression severity and episodic memory (auditory-verbal learning) impairment, in patients with MDD and with increased depression severity and attention impairment in patients with no depressive disorders. In patients with MIND, anhedonia did not correlate with depression severity or any cognitive performance score.

DISCUSSION

Our findings suggest that anhedonia is related to depression severity and specific cognitive performances in patients with MDD and with no depressive disorder. By contrast, the reduced hedonic tone in patients with MIND is independent from depression severity and cognition. Thus, anhedonia in PD is a heterogeneous and multidimensional phenomenon and require investigation at different levels.

Anxiety disorders, physical illnesses, and health care utilization in older male veterans with Parkinson disease and comorbid depression

This study examined the rates of anxiety and depressive disorders, physical illnesses, and health service use in male patients 55 years or older with a diagnosis of Parkinson disease who were seen at least twice at the 10 medical centers in the Veterans Affairs Healthcare Network of the South Central region of the United States. Of the 273 male patients diagnosed between October 1, 1997, and September 30, 2009, 62 (22.7%) had a depressive disorder. The overall prevalence of anxiety disorders was 12.8%; patients with comorbid depression had a 5-fold greater prevalence of anxiety disorders than those without depression (35.5% vs 6.2%, P<.0001). Patients with comorbid depression also had increased prevalence of all physical illnesses examined and more outpatient clinic and mental health visits. Patients with Parkinson disease and comorbid depression are more likely to have anxiety disorders and several physical illnesses, to be using antipsychotic and dementia medicines, and to have increased health service utilization than those without depression.

Mathematical insights into the effects of levodopa

Parkinson’s disease has been traditionally thought of as a dopaminergic disease in which cells of the substantia nigra pars compacta (SNc) die. However, accumulating evidence implies an important role for the serotonergic system in Parkinson’s disease in general and in physiological responses to levodopa therapy, the first line of treatment. We use a mathematical model to investigate the consequences of levodopa therapy on the serotonergic system and on the pulsatile release of dopamine (DA) from dopaminergic and serotonergic terminals in the striatum. Levodopa competes with tyrosine and tryptophan at the blood-brain barrier and is taken up by serotonin neurons in which it competes for aromatic amino acid decarboxylase. The DA produced competes with serotonin (5HT) for packaging into vesicles. We predict the time courses of LD, cytosolic DA, and vesicular DA in 5HT neurons during an LD dose. We predict the time courses of DA and 5HT release from 5HT cell bodies and 5HT terminals as well as the changes in 5HT firing rate due to lower 5HT release. We compute the time course of DA release in the striatum from both 5HT and DA neurons and show how the time course changes as more and more SNc cells die. This enables us to explain the shortening of the therapeutic time window for the efficacy of levodopa as Parkinson’s disease progresses. Finally, we study the effects 5HT1a and 5HT1b autoreceptor agonists and explain why they have a synergistic effect and why they lengthen the therapeutic time window for LD therapy. Our results are consistent with and help explain results in the experimental literature and provide new predictions that can be tested experimentally.

Is depression in Parkinson's disease (PD) a specific entity?

BACKGROUND

Clinical lore and research have suggested for a long time that depression and PD are closely related. We examined the validity of depression associated with PD (dPD) as a specific subtype of depression according to face validity, descriptive validity, construct validity and predictive validity.

METHODS

The English literature was reviewed after searching the MEDLINE database up to June 2010.

RESULTS

There appears to be three possible subtypes of comorbid depression: 1) patients who would have been depressed even if they had no PD (nonspecific-casual comorbid dPD), 2) patients who would have been depressed if they had had another disabling medical illness (nonspecific-reactive comorbid dPD) 3) those for which depression is directly related to the underlying pathophysiology of PD (specific comorbid dPD). These latter patients may more often present with particular clinical characteristics (descriptive validity): absence of history of depression or only within 5 years prior to onset of PD, absence of guilty thoughts and self-blame, absence of suicidal behavior, right-sided onset. However, dPD is only partly responsive to dopamine replacement and cannot be solely explained by dopamine deficiency. Other neurotransmitter systems are affected in PD and are involved in the pathophysiology of dPD. Their relative involvement however may differ from that in idiopathic depression (i.e.: lesser involvement of serotonergic systems).

LIMITATIONS

Therapeutic data are limited to few controlled trials.

CONCLUSIONS

Further research may allow differential diagnosis between dPD subtypes (i.e.: those who do and do not result from the underlying pathophysiological process of PD) and help inform treatment choice.

Neurologists' diagnostic accuracy of depression and cognitive problems in patients with parkinsonism

Background

Depression and cognitive impairment (CI) are important non-motor symptoms in Parkinson’s Disease (PD) and related syndromes, but it is not clear how well they are recognised in daily practice. We have studied the diagnostic performance of experienced neurologists on the topics depression and cognitive impairment during a routine encounter with a patient with recent-onset parkinsonian symptoms.

Methods

Two experienced neurologists took the history and examined 104 patients with a recent-onset parkinsonian disorder, and assessed the presence of depression and cognitive impairment. On the same day, all patients underwent a Hamilton Depression Rating Scale test, and a Scales for Outcomes in Parkinson’s Disease-Cognition-test (SCOPA-COG).

Results

The sensitivity of the neurologists for the topic depression was poor: 33.3%. However, the specificity varied from 90.8 to 94.7%. The patients’ sensitivity was higher, although the specificity was lower. On the topic CI, the sensitivity of the neurologists was again low, in a range from 30.4 up to 34.8%: however the specificity was high, with 92.9%. The patients’ sensitivity and specificity were both lower, compared to the number of the neurologists.

Conclusions

Neurologists’ intuition and clinical judgment alone are not accurate for detection of depression or cognitive impairment in patients with recent-onset parkinsonian symptoms because of low sensitivity despite of high specificity.

Trial registration

(ITRSCC)NCT0036819.

Depression in Parkinson's disease

Among the recently well appreciated non-motor symptoms in Parkinson's disease (PD), depression plays a prominent role due to its frequency and impact on quality of life. However, depression may be confounded by motor symptoms, especially akinesia and other non-motor symptoms such as apathy, anxiety and dementia. Data on specific diagnostic tools or treatment for depressive symptoms in PD patients are still sparse. Here we summarize an expert opinion based on available data and clinical experience.

Nonmotor disorders and their correlation with dopamine: can they be treated by currently available methods?

Many of the nonmotor symptoms in Parkinson disease have a dopaminergic basis, whether the result of dopaminergic degeneration or as a result of dopaminergic treatment. In the latter case, the symptoms may be genuine side effects of drugs (hypotension, pathologic gambling, etc.) or they may be secondary either to the pathoplastic effect they have on the natural course of the disease (nonmotor fluctuations) or to the lack of dopamine (apathy, depression, dopamine withdrawal syndrome, etc.). In all these cases, dopaminergic treatment can be helpful. However, many other nonmotor (and motor) symptoms will have no correlation with dopamine; therefore, they require different treatments, very often with little efficacy, as in apathy or cognitive decline.

Validity and reliability assessment of a Japanese version of the Snaith-Hamilton pleasure scale

OBJECTIVE

Anhedonia is one of the main non-motor symptoms in Parkinson's disease (PD); it is assessed using the Snaith-Hamilton pleasure scale (SHAPS). To assess anhedonia in the Japanese population, we prepared a Japanese language version of SHAPS (SHAPS-J), and evaluated its validity and reliability in 8 neurological centers. Seventy subjects (48 patients with PD and 22 healthy subjects) were enrolled in this study.

METHODS

The validity of the test was assessed by the correlation between SHAPS-J and the apathy scale, based on the fact that anhedonia is considered a symptom of apathy syndrome. Test-retest reliability and internal consistency were assessed by Cohen's kappa and Cronbach's alpha coefficients, respectively.

RESULTS

In the evaluation of validity, the total scores obtained on SHAPS-J during the test and retest significantly correlated with scores on Item 4 in Part 1 of the unified Parkinson's disease rating scale (p<0.0008 and p<0.0036, respectively). Cohen's kappa coefficient was >0.3 on all items (p<0.0005 on all items). Cronbach's alpha coefficient was 0.90 at the baseline and 0.88 at the retest.

CONCLUSION

These results indicate that SHAPS-J has good validity, test-retest reliability, and internal consistency, thus establishing an available measure of anhedonia in Japanese.

Anhedonia in Japanese patients with Parkinson's disease: analysis using the Snaith-Hamilton Pleasure Scale

BACKGROUND

Anhedonia, a lowered ability to experience physical or social pleasure, has recently been recognized as a non-motor symptom of Parkinson's disease.

OBJECTIVE

To identify the frequency of anhedonia and the factors influencing hedonic tone in Japanese patients with Parkinson's disease.

PATIENTS AND METHODS

We recruited 86 consecutive outpatients with a clinical diagnosis of PD attending two Japanese hospitals (one university hospital and one community hospital) in February 2010. We used the self-rating Snaith-Hamilton Pleasure Scale (SHAPS) translated into Japanese language from the original English version to assess and quantify hedonic tone as a subjectively experienced phenomenon. We studied the association of anhedonia with the variables age, age at onset, gender, disease duration, disease severity and antiparkinsonian drugs.

RESULTS

Thirty-nine patients (45%) were male and 47 (55%) were female. Mean age was 72.01±9.07 (49-89) years, with mean age at onset of 64.93±11.42 (31-88) years. Mean disease duration was 7.20±5.54 (1-23) years. The mean Hoehn and Yahr scale was 2.76±0.78. The mean SHAPS score of the total sample was 1.19±1.86. The SHAPS score of 14 patients (16.3%) was 3 or more, indicating anhedonia. The mean SHAPS score was lower in patients taking pramipexole (0.58±0.97) than in patients not taking pramipexole (1.57±2.16). Multiple linear regression analysis identified pramipexole as a significant negative influencing factor on the SHAPS score, while disease severity and entacapone treatment were identified as positive influencing factors. The age, onset age, gender, disease duration, and use of pergolide, amantadine, zonisamide, selegiline, anticholinergic agents and droxidopa did not significantly affect the SHAPS score.

CONCLUSION

Anhedonia is not rare non-motor symptom in Japanese patients with Parkinson's disease. This study suggests an anti-anhedonic property of pramipexole.

Neurological diseases and pain

Chronic pain is a frequent component of many neurological disorders, affecting 20-40% of patients for many primary neurological diseases. These diseases result from a wide range of pathophysiologies including traumatic injury to the central nervous system, neurodegeneration and neuroinflammation, and exploring the aetiology of pain in these disorders is an opportunity to achieve new insight into pain processing. Whether pain originates in the central or peripheral nervous system, it frequently becomes centralized through maladaptive responses within the central nervous system that can profoundly alter brain systems and thereby behaviour (e.g. depression). Chronic pain should thus be considered a brain disease in which alterations in neural networks affect multiple aspects of brain function, structure and chemistry. The study and treatment of this disease is greatly complicated by the lack of objective measures for either the symptoms or the underlying mechanisms of chronic pain. In pain associated with neurological disease, it is sometimes difficult to obtain even a subjective evaluation of pain, as is the case for patients in a vegetative state or end-stage Alzheimer's disease. It is critical that neurologists become more involved in chronic pain treatment and research (already significant in the fields of migraine and peripheral neuropathies). To achieve this goal, greater efforts are needed to enhance training for neurologists in pain treatment and promote greater interest in the field. This review describes examples of pain in different neurological diseases including primary neurological pain conditions, discusses the therapeutic potential of brain-targeted therapies and highlights the need for objective measures of pain.

Stress, depression and Parkinson's disease

In this review, we focus on the relationship among Parkinson's disease (PD), stress and depression. Parkinson's disease patients have a high risk of developing depression, and it is possible that stress contributes to the development of both pathologies. Stress dysfunction may have a role in the etiology of preclinical non-motor symptoms of PD (such as depression) and, later in the course of the disease, may worsen motor symptoms. However, relatively few studies have examined stress or depression and the injured nigrostriatal system. This review discusses the effects of stress on neurodegeneration and depression, and their association with the symptoms and progression of PD.

Religious and spiritual beliefs in outpatients suffering from Parkinson Disease

OBJECTIVE

Personality changes are known to occur in idiopathic Parkinson's Disease (PD). The aim of the study was to evaluate whether religious and spiritual beliefs in PD patients are different from age-matched controls.

DESIGN

Eighty-three PD participants, 79 hypertensive individuals not affected by PD and 88 healthy subjects participated to a cross-sectional study. The Royal Free Interview (RFI) was used to evaluate participants' beliefs. The Hospital Anxiety and Depression Scale (HADS) was applied to monitor emotional distress.

RESULTS

There was no statistical evidence of a difference between PD participants and the two control groups, the only exception being observed between the left PD onset group and the controls, where the total RFI score was about 5 points higher (t-test: p = 0.0273). RFI total score was uncorrelated with age, severity of illness and depression, but was strongly dependent on the type of beliefs. The percentage of PD participants suffering from anxiety and depression was high (right onset: 54.8%; left onset: 68.6%), while only 15.2% of the hypertensive participants, and none of the healthy controls, had a HADS score above 10 points. Total RFI score was higher in women.

CONCLUSION

PD participants maintain their Faith in spite of the disease severity. Differences are found between right and left onset of PD. The possible beneficial effect of religious coping is discussed.

Anhedonia in Parkinson's disease: a systematic review of the literature

Anhedonia, defined as lowered ability to experience physical or social pleasure, is a key symptom of several psychiatric illnesses. In this systematic review, we aimed to evaluate the role of anhedonia in Parkinson's Disease and its relationships with other clinical characteristics, dopamine dysfunction, and antiparkinsonian therapy. The database was selected using PubMed Services. Relevant journals were hand-searched, and the bibliographies of all the important articles were scrutinized to find additional publications. Fifteen studies assessed the topic of anhedonia in Parkinson's disease from 1984 to 2009 and mainly described it as a core symptom of depression in patients with Parkinson's disease. Some studies investigated the relationship between anhedonia and neuropsychological symptoms and found correlations with frontal lobe functions. Reports on the relationship between anhedonia and illness severity or motor symptoms are rather inconclusive. No definitive conclusions can be drawn because few studies have been published on this topic. Nevertheless, some evidence suggests that in Parkinson's disease anhedonia is a secondary phenomenon linked to depression, apathy severity, and frontal lobe dysregulation and that it could respond to antiparkinsonian treatment. Future studies of larger samples of patients are strongly required to definitively clarify the relationship between anhedonia and other clinical features, such as depression, anxiety, apathy, cognition, and motor status. Furthermore, more reliable tools and validated diagnostic criteria are necessary to assess anhedonia in patients with Parkinson's disease.

Depressogenic effects of medications: a review

The literature is filled with reports that link medications with the onset or progression of depression. Because depression is so common in patients with medical illness, assessing whether a medication has in fact caused depression, or whether the relationship is coincidental, can be challenging. In this article, we review the literature on the association between medications and depression. For most agents, there are case reports or small studies linking the medication with the onset of depression, but more rigorous prospective studies are either lacking or found no association between the agent and depression. However, several medications, (eg, barbiturates, vigabatrin, topiramate, flunarizine, corticosteroids, mefloquine, efavirenz, and interferon-α) do appear to cause depression in some patients and should be used with caution in patients at risk for depression.

The impact of left prefrontal repetitive transcranial magnetic stimulation on depression in Parkinson's disease: a randomized, double-blind, placebo-controlled study

Based on several open-label and case studies, repetitive transcranial magnetic stimulation (rTMS) seems to have an antidepressive effect on patients with Parkinson's disease (PD). However, this hypothesis requires further confirmation. We conducted a randomized, double-blind placebo-controlled study to evaluate the effect of rTMS over the left dorsolateral prefrontal cortex (DLPFC) on depression and various motor and nonmotor features of PD. Twenty-two PD patients with mild or moderate depressive episodes were assigned into two groups, one receiving real-rTMS (90% of resting motor threshold, 5 Hz, 600 pulses-a-day for 10 days) over the left DLPFC, and another group receiving sham-rTMS. An investigator blinded to the treatment performed three video-taped examinations on each patient: before stimulation (baseline), 1 day (short term), and 30 days after treatment session ended (long-term effect). Mini-Mental State Examination, Unified Parkinson's Disease Rating Scale (UPDRS), Hoehn-Yahr, Epworth Sleepiness, Visual Analog and Montgomery-Asberg Depression Rating Scales (MADRS), Beck Depression Inventory (BDI), and Trail making and Stroop tests were applied. In the actively treated group, not only depression rating scales showed significant improvement 30 days after treatment ended (BDI by 44.4% and MADRS by 26.1%), but also the accuracy of Stroop test (by 16%). We could also demonstrate an insignificant improvement in UPDRS-III by 7.5 points (31.9%, P = 0.06). In the sham-treated group none of the examined tests and scales improved significantly after sham stimulation. Our study demonstrated the beneficial effect of the left DLPFC rTMS on depression in PD lasting at least 30 days after treatment. However, this result should be confirmed in patients with severe depression by further clinical trials.

Diagnostic accuracy and agreement across three depression assessment measures for Parkinson's disease

PURPOSE

To assess diagnostic accuracy of two self-administered depression measures compared to an interviewer-administered measure in subjects with Parkinson's disease (PD), and to analyze clinical and sociodemographic factors associated with disagreement among the three depression assessment tools.

METHODS

We assessed 214 PD subjects using the Patient Health Questionnaire-9 (PHQ-9), the Geriatric Depression Scale-15 (GDS-15), and the Structured Clinical Interview for the DSM-IV depression module (SCID). Diagnostic accuracy of the PHQ-9 and GDS-15 compared to the SCID was evaluated. Multivariate logistic regression was conducted to analyze factors associated with measure disagreement. We compared item agreement between the PHQ-9 and SCID to test the hypothesis that there would be less agreement between items assessing depression symptoms overlapping with common PD symptoms, compared to items having minimal overlap with PD manifestations.

RESULTS

Compared to SCID diagnosis of major depression, PHQ-9 sensitivity is 50% and specificity is 93%; GDS-15 sensitivity is 43% and specificity is 96%. The GDS-15 has 85% sensitivity and 79% specificity and the PHQ-9 has 54% sensitivity and 85% specificity compared to SCID diagnosis of minor or major depression. The PHQ-9 and SCID show more agreement on items unrelated to PD manifestations. Pain was the only factor associated with disagreement between the SCID and PHQ-9.

CONCLUSION

Compared to the PHQ-9, the GDS-15 had higher sensitivity and similar positive predictive value, suggesting it is a superior screening tool in clinical applications for PD. On future depression screening or diagnostic instruments, consideration should be given to excluding depression items overlapping with PD manifestations.

Occurrence of depression and anxiety prior to Parkinson's disease

OBJECTIVE

To assess the relationship between depression and anxiety and Parkinson's disease (PD).

BACKGROUND

Many people with PD suffer from depression and anxiety prior to the onset of motor symptoms. Studies suggest these psychiatric conditions may be risk factors for PD or prodromal non-motor symptoms.

METHODS

Using a population-based approach in three California counties, we recruited 371 incident PD cases, 402 population and 115 sibling controls. We recorded self-reports of lifetime depression/anxiety diagnoses and use of psychotropic medications. We adjusted for age, race, sex, pack-years of smoking, and education, and also conducted analyses after excluding (lagging) both diagnoses and medication use first occurring within 2, 5, 10, and 20 years of the index/diagnosis date.

RESULTS

Cases were more likely to have received a diagnosis of depression or anxiety at any time prior to index date (OR 1.42, 95% CI 1.01, 2.00), but were not more likely to have been both diagnosed and treated (OR 1.11, 95% CI 0.77, 1.60). Male PD patients received diagnoses combined with treatment more often than population controls within 5 years of PD diagnosis (OR 2.21, 95% CI 1.21, 4.04; 2 year lag: OR 2.44, 95% CI 1.29, 4.61; 5 year lag: OR 1.67, 95% CI 0.80, 3.49). We did not see any differences for females. Results for cases compared to sibling controls were similar to those for population controls.

CONCLUSION

These results suggest that depression and anxiety may be early symptoms during the prodromal phase of PD.

Gait variability in Parkinson's disease: an indicator of non-dopaminergic contributors to gait dysfunction?

Gait variability has potential utility as a predictive measure of dysfunction in Parkinson's disease (PD). Current understanding implicates non-dopaminergic pathways. This study investigated the explanatory characteristics of gait variability in PD on and off medication under single and dual task conditions. Fifty people with PD were assessed twice at home (on and off L: -dopa) whilst walking under single and dual task conditions, and variability (coefficient of variation, CV) was calculated for stride time and double limb support (DLS) time. Hierarchical regression analysis was used to identify predictors. The first block of variables included age, gait speed, depression (Hospital Anxiety and Depression Scale) and fatigue (Multidimensional Fatigue Inventory), and the second block included motor severity (UPDRS III), executive function (Hayling and Brixton) and attention (Test of Everyday Attention). Motor severity predicted stride time variability and DLS time variability independent of L: -dopa during single task gait. Dual task gait yielded a more complex picture. Depression made a unique contribution of 9.0% on medication and 5.0% off medication to stride time variability, and visual attention and younger age contributed to DLS variability on medication, explaining 3% and 2%, respectively. Motor severity predicted DLS variability off medication, explaining 74% of variance. Different characteristics explain the two measures of gait variability, pointing to different control mechanisms.

Cabergoline, a dopamine receptor agonist, has an antidepressant-like property and enhances brain-derived neurotrophic factor signaling

RATIONALE

Dopamine agonists have been implicated in the treatment of depression. Cabergoline is an ergot derivative with a high affinity to dopamine D(2)-like receptors; however, there have been few preclinical studies on its antidepressant-like effects.

MATERIALS AND METHODS

Behavioral effects of cabergoline were examined in rats using forced swimming (FST), novelty-suppressed feeding (NST), open field (OFT), and elevated-plus maze (EPT) tests. In a single treatment paradigm, behaviors of rats were analyzed 4 h after single injection of cabergoline (s.c., 0-4 micromol/kg). In a repeated-treatment paradigm, OFT, EPT, and FST were conducted on days 11, 12, and 13-14, respectively, during daily cabergoline injections (s.c., 0.5 micromol/kg), and then hippocampus was removed 24 h after the last injection. NST was conducted in a separate experiment at day 14. Western blotting was used for the analysis of the protein levels of brain-derived neurotrophic factor (BDNF) and the activation of intracellular signaling molecules.

RESULTS

Single injection of cabergoline demonstrated decreased immobility in FST and distance traveled during 0-10 min in OFT, while time spent and entry into open arms were increased at 4 micromol/kg. When cabergoline was repeatedly administered, immobility in FST and the latency of feeding in NSF were significantly reduced, while vertical movement was increased in OFT. The time in closed arms was tended to be decreased in EPT. Expression of BDNF and activation of extracellular signal-regulated kinase 1 were up-regulated after the chronic administration of cabergoline.

CONCLUSIONS

Cabergoline exerts antidepressant- and anxiolytic-like effects, which may be mediated by potentiation of intracellular signaling of BDNF.

Potential mechanisms underlying anxiety and depression in Parkinson's disease: consequences of l-DOPA treatment

Though the most recognizable symptoms of Parkinson's disease (PD) are motor-related, many patients also suffer from debilitating affective symptoms that deleteriously influence quality of life. Dopamine (DA) loss is likely involved in the onset of depression and anxiety in PD. However, these symptoms are not reliably improved by DA replacement therapy with l-3,4-dihydroxyphenylalanine (l-DOPA). In fact, preclinical and clinical evidence suggests that l-DOPA treatment may worsen affect. Though the neurobiological mechanisms remain unclear, recent research contends that l-DOPA further perturbs the function of the norepinephrine and serotonin systems, already affected by PD pathology, which have been intimately linked to the development and expression of anxiety and depression. As such, this review provides an overview of the clinical characteristics of affective disorders in PD, examines the utility of animal models for the study of anxiety and depression in PD, and finally, discusses potential mechanisms by which DA loss and subsequent l-DOPA therapy influence monoamine function and concomitant affective symptoms.

Exercise effects on motor and affective behavior and catecholamine neurochemistry in the MPTP-lesioned mouse

This study used 1-methyl-4-phenyl-1,2,3,6,-tetrahydropyridine (MPTP) in mice to determine if exercise improves behavior and dopamine (DA) and serotonin (5HT) content. Male C57BL/6 mice received MPTP (4 x 20mg/kg) or saline. They remained sedentary or exercised by treadmill or voluntary running wheel for 6 weeks (n=8/group). Saline-treated mice ran significantly faster on running wheels (22.8+/-1.0m/min) than on treadmill (8.5+/-0.5m/min), and MPTP lesion did not reduce voluntary exercise (19.3+/-1.5m/min, p>0.05). There was a significant effect of both lesion and exercise on overall Rotarod performance (ORP): MPTP lesion reduced ORP, while treadmill exercise increased ORP vs sedentary mice (p<0.05). MPTP increased anxiety in the marble-burying test: sedentary lesioned mice buried more marbles (74.0+/-5.2%) than sedentary controls (34.8+/-11.8%, p<0.05). Conversely, exercise reduced anxiety on the elevated plus maze. Among saline-treated mice, those exposed to voluntary wheel-running showed an increased percent of open arm entries (49.8+/-3.5%, p<0.05) relative to sedentary controls (36.2+/-4.0%, p<0.05). Neither MPTP nor exercise altered symptoms of depression measured by sucrose preference or tail suspension. MPTP significantly reduced DA in striatum (in sedentary lesioned mice to 42.1+/-3.0% of saline controls), and lowered 5HT in amygdala and striatum (in sedentary lesioned mice to 86.1+/-4.1% and 66.5+/-8.2% of saline controls, respectively); exercise had no effect. Thus, exercise improves behavior in a model of DA depletion, without changes in DA or 5HT.

Occurrence risk and structure of depression in Parkinson disease with and without dementia: results from the GEPAD Study

BACKGROUND

This study examined the age- and gender-specific risk of depression in demented and non-demented participants, its symptom structure, and associated clinical factors in a nationwide random sample of n = 1449 outpatients with Parkinson disease (PD).

METHODS

Depression ratings were based on a cross-sectional clinical assessment including the clinical Montgomery-Asberg Depression Rating Scale (MADRS > or = 14). Parkinson disease severity was rated according to Hoehn and Yahr (HY) and the Unified Parkinson's Disease Rating Scale. Diagnosis of dementia was based on Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition; DSM-IV) criteria.

RESULTS

25.2% (CI: 22.8-27.5) of all patients met study criteria for depression. Additionally, 8.4% of patients did not exceed the MADRS cut-off but were currently being treated with antidepressants, possibly suggesting a corrected (upper limit) total prevalence of 33.6%. Females were more likely depressive than males (29.3% vs 22.4%). In both genders, depression risk was elevated 2- to 4-fold depending on HY stage. Overall, highest rates in non-demented patients were found in females at stages IV to V (53.7%, CI: 37.7-69.6). Demented patients were more likely to meet depression criteria than non-demented (up to 76.2%, 95% CI: 60.5-87.9). Depression symptom profiles for demented PD patients (as compared to non-demented) revealed no structural differences but consistently higher symptom scores. Neither age at onset of PD nor duration of disease were significantly linked with depression.

CONCLUSIONS

Depression rates are already substantially elevated at early PD stages, emphasizing the need for a thorough examination of mood disorders in all patients with PD. Depression is associated with PD severity and dementia but not with age, age at onset of PD, or disease duration. The differential associations with dementia and the statistical independence of dementia and depression also suggest that depression could not be regarded as a mere demoralisation syndrome.

Apathy and depression in Parkinson disease

The purpose of this study was to investigate the prevalence and clinical correlates of apathy and depression in Parkinson disease (PD), and to clarify whether apathy can be dissociated from depression. One hundred fifty patients with PD completed the Beck Depression Inventory Second Edition (BDI-II), Starkstein's Apathy Scale (AS), and a quality of life (QOL) battery. Hoehn and Yahr (HY) staging, the Unified Parkinson's Disease Rating Scale (UPDRS), and the Mini-Mental State Examination (MMSE) were performed on the same day. Apathy (AS score > or = 16) was diagnosed in 60% of patients and depression (BDI-II score > or = 14) in 56%. Apathy coexisted with depression in 43% of patients, compared with depression without apathy in 13% and apathy without depression in 17%. Apathy scale score was significantly correlated with UPDRS scores, HY stage, and age, whereas BDI-II score was correlated only with UPDRS scores. Both AS and BDI-II scores were negatively correlated with QOL. However, multiple regression analysis revealed that depression was strongly and negatively associated with emotional well-being and communication, whereas apathy was mainly associated with cognition and stigma. These findings suggest that apathy and depression may be separable in PD, although both are common in patients with PD and are associated with QOL.

Destruction of dopaminergic neurons in the midbrain by 6-hydroxydopamine decreases hippocampal cell proliferation in rats: reversal by fluoxetine

Background

Non-motor symptoms (e.g., depression, anxiety, and cognitive deficits) in patients with Parkinson disease (PD) precede the onset of the motor symptoms. Although these symptoms do not respond to pharmacological dopamine replacement therapy, their precise pathological mechanisms are currently unclear. The present study was undertaken to examine whether the unilateral 6-hydroxydopamine (6-OHDA) lesion to the substantia nigra pars compacta (SNc), which represents a model of long-term dopaminergic neurotoxicity, could affect cell proliferation in the adult rat brain. Furthermore, we examined the effects of the selective serotonin reuptake inhibitor (SSRI) fluoxetine and the selective noradrenaline reuptake inhibitor maprotiline on the reduction in cell proliferation in the subgranular zone (SGZ) by the unilateral 6-OHDA lesion.

Methodology/Principal Findings

A single unilateral injection of 6-OHDA into the rat SNc resulted in an almost complete loss of tyrosine hydroxylase (TH) immunoreactivity in the striatum and SNc, as well as in reductions of TH-positive cells and fibers in the ventral tegmental area (VTA). On the other hand, an injection of vehicle alone showed no overt change in TH immunoreactivity. A unilateral 6-OHDA lesion to SNc significantly decreased cell proliferation in the SGZ ipsilateral to the 6-OHDA lesion, but not in the contralateral SGZ or the subventricular zone (SVZ), of rats. Furthermore, subchronic (14 days) administration of fluoxetine (5 mg/kg/day), but not maprotiline significantly attenuated the reduction in cell proliferation in the SGZ by unilateral 6-OHDA lesion.

Conclusions/Significance

The present study suggests that cell proliferation in the SGZ of the dentate gyrus might be, in part, under dopaminergic control by SNc and VTA, and that subchronic administration of fluoxetine reversed the reduction in cell proliferation in the SGZ by 6-OHDA. Therefore, SSRIs such as fluoxetine might be potential therapeutic drugs for non-motor symptoms as well as motor symptoms in patients with PD, which might be associated with the reduction in cell proliferation in the SGZ.

Cortical serotonin and norepinephrine denervation in parkinsonism: preferential loss of the beaded serotonin innervation

Parkinson's Disease (PD) is marked by prominent motor symptoms that reflect striatal dopamine insufficiency. However, non-motor symptoms, including depression, are common in PD. It has been suggested that these changes reflect pathological involvement of non-dopaminergic systems. We examined regional changes in serotonin (5-HT) and norepinephrine (NE) systems in mice treated with two different 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment paradigms, at survival times of 3 or 16 weeks after the last MPTP injection. MPTP caused a decrease in striatal dopamine concentration, the magnitude of which depended on the treatment regimen and survival interval after MPTP treatment. There was significant involvement of other subcortical areas receiving a dopamine innervation, but no consistent changes in 5-HT or NE levels in subcortical sites. In contrast, we observed an enduring decrease in 5-HT and NE concentrations in both the somatosensory cortex and medial prefrontal cortex (PFC). Immunohistochemical studies also revealed a decrease in the density of PFC NE and 5-HT axons. The decrease in the cortical serotonergic innervation preferentially involved the thick beaded but not smooth fine 5-HT axons. Similar changes in the 5-HT innervation of post-mortem samples of the PFC from idiopathic PD cases were seen. Our findings point to a major loss of the 5-HT and NE innervations of the cortex in MPTP-induced parkinsonism, and suggest that loss of the beaded cortical 5-HT innervation is associated with a predisposition to the development of depression in PD.

Cognitive and personality features in Parkinson disease: 2 sides of the same coin?

OBJECTIVE

This study seeks to identify the possible relationship between certain executive functions and the main personality traits in 25 nondemented Parkinson disease (PD) patients.

BACKGROUND

Both the presence of cognitive changes-mainly concerning executive functions-and peculiar personality traits, such as low novelty seeking, moral rigidity, industriousness, or introversion, were fully documented in PD patients.

METHODS

Patients underwent the Tower of London test and Alternating Fluency tasks for planning abilities and cognitive flexibility to be assessed. Personality features were evaluated using the Big Five Adjectives checklist.

RESULTS

The study provided evidence of a significant correlation between the Tower of London and the Emotional Stability factor and between Alternating Fluencies and the Openness to Experience factor.

CONCLUSIONS

The Tower of London test and the Emotional Stability factor may require filtering of irrelevant information, activation of inhibition mechanisms, and use of negative feedback. The Alternating Fluency tasks and the Openness to Experience factor may require the ability to switch set and to express flexible thoughts or opinions in daily life. These results indicate that cognitive and personality changes in PD may be different expressions of a common psychologic mechanism related to the dysfunction of the frontostriatal system.

Neurotransmission in Parkinson's disease: beyond dopamine

Parkinson's disease (PD) is most frequently associated with characteristic motor symptoms that are known to arise with degeneration of dopaminergic neurons. However, patients with this disease also experience a multitude of non-motor symptoms, such as sleep disturbances, fatigue, apathy, anxiety, depression, cognitive impairment, dementia, olfactory dysfunction, pain, sweating and constipation, some of which can be at least as debilitating as the movement disorders and have a major impact on patients' quality of life. Many of these non-motor symptoms may be evident prior to the onset of motor dysfunction. The neuropathology of PD has shown that complex, interconnected neuronal systems, regulated by a number of different neurotransmitters in addition to dopamine, are involved in the aetiology of motor and non-motor symptoms. This review focuses on the non-dopaminergic neurotransmission systems associated with PD with particular reference to the effect that their modulation and interaction with dopamine has on the non-motor symptoms of the disease. PD treatments that focus on the dopaminergic system alone are unable to alleviate both motor and non-motor symptoms, particularly those that develop at early stages of the disease. The development of agents that interact with several of the affected neurotransmission systems could prove invaluable for the treatment of this disease.

kappa-Opioid receptor signaling and brain reward function

The dynorphin-like peptides have profound effects on the state of the brain reward system and human and animal behavior. The dynorphin-like peptides affect locomotor activity, food intake, sexual behavior, anxiety-like behavior, and drug intake. Stimulation of kappa-opioid receptors, the endogenous receptor for the dynorphin-like peptides, inhibits dopamine release in the striatum (nucleus accumbens and caudate putamen) and induces a negative mood state in humans and animals. The administration of drugs of abuse increases the release of dopamine in the striatum and mediates the concomitant release of dynorphin-like peptides in this brain region. The reviewed studies suggest that chronic drug intake leads to an upregulation of the brain dynorphin system in the striatum and in particular in the dorsal part of the striatum/caudate putamen. This might inhibit drug-induced dopamine release and provide protection against the neurotoxic effects of high dopamine levels. After the discontinuation of chronic drug intake these neuroadaptations remain unopposed which has been suggested to contribute to the negative emotional state associated with drug withdrawal and increased drug intake. kappa-Opioid receptor agonists have also been shown to inhibit calcium channels. Calcium channel inhibitors have antidepressant-like effects and inhibit the release of norepinephrine. This might explain that in some studies kappa-opioid receptor agonists attenuate nicotine and opioid withdrawal symptomatology. A better understanding of the role of dynorphins in the regulation of brain reward function might contribute to the development of novel treatments for mood disorders and other disorders that stem from a dysregulation of the brain reward system.

Demonstration of disturbed activity of external globus pallidus projecting neurons in depressed patients by the AgNOR staining method

BACKGROUND

The external globus pallidus (EGP) is thought to play the most important integrating and conveying role in the striatopallidal system involved in the transfer from motivation to action. The aim to find a morphological biomarker of disturbed EGP activity in depression was approached by the karyometric analysis of large projecting neurons.

METHODS

The study was performed on paraffin-embedded brains from 19 depressed patients from both the major depressive disorder (MDD) and the bipolar disorder (BD) diagnostic groups encompassing 10 suicides and from 24 controls. The karyometric parameters of EGP neurons bilaterally were evaluated by argyrophilic nucleolar organiser (AgNOR) silver staining method.

RESULTS

A significantly decreased AgNOR area was found in the left EGP neurons in depressed patients compared to controls. The distinctness of the diagnostic groups and suicidal vs non-suicidal patients was not shown in the statistical comparisons. The AgNOR parameter which was decreased correlated positively with the mean dose of benzodiazepines in non-suicidal patients.

LIMITATIONS

A major limitation of this study is the relatively small number of cases. A further limitation is given by the lack of data on drug exposure across the whole lifespan of patients.

CONCLUSION

The results suggest disturbed, most likely decreased, activity of the left EGP projecting neurons in depressed patients, a disturbed activity that should hypothetically be counteracted by the applied pharmacotherapy in non-suicidal patients.

Interferon-gamma deficiency modifies the motor and co-morbid behavioral pathology and neurochemical changes provoked by the pesticide paraquat

In addition to nigrostriatal pathology and corresponding motor disturbances, Parkinson's disease (PD) is often characterized by co-morbid neuropsychiatric symptoms, most notably anxiety and depression. Separate lines of evidence indicate that inflammatory processes associated with microglial activation and cytokine release may be fundamental to the progression of both PD and its co-morbid psychiatric pathology. Accordingly, we assessed the contribution of the pro-inflammatory cytokine, interferon-gamma (IFN-gamma), to a range of PD-like pathology provoked by the ecologically relevant herbicide and dopamine (DA) toxin, paraquat. To this end, paraquat provoked overt motor impairment (reduced home-cage activity and impaired vertical climbing) and signs of anxiety-like behavior (reduced open field exploration) in wild-type but not IFN-gamma-deficient mice. Correspondingly, paraquat promoted somewhat divergent variations in neurochemical activity among wild-type and IFN-gamma null mice at brain sites important for both motor (striatum) and co-morbid affective pathologies (dorsal hippocampus, medial prefrontal cortex, and locus coeruleus). Specifically, the herbicide provoked a dosing regimen-dependent reduction in striatal DA levels that was prevented by IFN-gamma deficiency. In addition, the herbicide influenced serotonergic and noradrenergic activity within the dorsal hippocampus and medial prefrontal cortex; and elevated noradrenergic activity within the locus coeruleus. Although genetic ablation of IFN-gamma had relatively few effects on monoamine variations within the locus coeruleus and prefrontal cortex, loss of the pro-inflammatory cytokine did normalize the paraquat-induced noradrenergic alterations within the hippocampus. These findings further elucidate the functional implications of paraquat intoxication and suggest an important role for IFN-gamma in the striatal and motor pathology, as well as the co-morbid behavioral and hippocampal changes induced by paraquat.

Brainstem pathology and non-motor symptoms in PD

Parkinson's disease (PD) is considered a multisystem disorder involving dopaminergic, noradrenergic, serotoninergic, and cholinergic systems, characterized by motor and non-motor symptoms. The causes of the non-motor symptoms in PD are multifactorial and unlikely to be explained by single lesions. However, several evidence link them to damage of specific brainstem nuclei. Numerous brainstem nuclei are engaged in fundamental homeostatic mechanisms, including gastrointestinal regulation, pain perception, mood control, and sleep-wake cycles. In addition, these nuclei are locally interconnected in a complex manner and are subject to supraspinal control. The objective of this review is to provide a better overview of the current knowledge about the consequences of the involvement of specific brainstem nuclei to the most prevalent non-motor symptoms occurring in PD. The multidisciplinary efforts of research directed to these non-nigral brainstem nuclei, in addition to the topographical and chronological spread of the disease - especially in the prodromal stages of PD, are discussed.

Subthreshold depression in Parkinson's disease

OBJECTIVE

It is estimated that 40% of patients with Parkinson's disease (PD) are clinically depressed, however, little is known about the frequency and associated features of subthreshold depression in PD. The current study sought to determine the prevalence of subthreshold depression (sD) and to further characterize the associated features in a sample of 111 nondemented patients with moderate to severe PD.

METHODS

Patients were classified into the following groups: diagnostic depression (DD), subthreshold depression (sD), or nondepressed (ND) by applying the Diagnostic and Statistical Manual, 4th edn criteria for depression and previously reported criteria for sD to items from the Beck Depression Inventory, 2nd edn. These groups were compared on clinical and demographic variables. The symptom profile of the sD group is also described.

RESULTS

Fifty participants (45.0%) were classified as ND, 32 (28.8%) as sD, and 29 (26.1%) as DD. Patients with sD were younger (approximately 5 yrs) than nondepressed patients, but did not differ in disease stage or any other demographic variables. Patients with sD tended to endorse mood symptoms that overlap with PD, including fatigue, sleep difficulties, appetite dysfunction, and concentration difficulties. These symptoms were also endorsed with high frequency by the other groups.

CONCLUSIONS

These findings suggest that sD is not uncommon in PD and may be more prevalent among younger patients. The finding that sD patients report mood symptoms that overlap with the PD symptomatology suggests that these two entities share common features and may be difficult to disentangle.

Characterization of the potent and highly selective A2A receptor antagonists preladenant and SCH 412348 [7-[2-[4-2,4-difluorophenyl]-1-piperazinyl]ethyl]-2-(2-furanyl)-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine] in rodent models of movement disorders and depression

The adenosine A(2A) receptor has been implicated in the underlying biology of various neurological and psychiatric disorders, including Parkinson's disease (PD) and depression. Preladenant and SCH 412348 [7-[2-[4-2,4-difluorophenyl]-1-piperazinyl]ethyl]-2-(2-furanyl)-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine] are potent competitive antagonists of the human A(2A) receptor (K(i) = 1.1 and 0.6 nM, respectively) and have >1000-fold selectivity over all other adenosine receptors, making these compounds the most selective A(2A) receptor antagonists reported to date. Both compounds attenuate hypolocomotion induced by the A(2A) receptor agonist CGS-21680 [2-[p-(2-carboxyethyl)phenethylamino]-5'-N-ethylcarboxamidoadenosine], suggesting that they inhibit A(2A) receptor activity in vivo. Their high degree of selectivity and robust in vivo activity make preladenant and SCH 412348 useful tools to investigate the role of the A(2A) receptor system in animal models of PD and depression. Oral administration of preladenant and SCH 412348 (0.1-1 mg/kg) to rats potentiated 3,4-dihydroxy-L-phenylalanine (L-Dopa)-induced contralateral rotations after 6-hydroxydopamine lesions in the medial forebrain bundle and potently attenuated the cataleptic effects of haloperidol. Preladenant (1 mg/kg) inhibited L-Dopa-induced behavioral sensitization after repeated daily administration, which suggests a reduced risk of the development of dyskinesias. Finally, preladenant and SCH 412348 exhibited antidepressant-like profiles in models of behavioral despair, namely the mouse tail suspension test and the mouse and rat forced swim test. These studies demonstrate that preladenant and SCH 412348 are potent and selective A(2A) receptor antagonists and provide further evidence of the potential therapeutic benefits of A(2A) receptor inhibition in PD (with reduced risk of dyskinesias) and depression (one of the primary nonmotor symptoms of PD).