Atomoxetine for depression and other neuropsychiatric symptoms in Parkinson disease

Off-label use of atomoxetine in adults: is it safe?

Atomoxetine has been approved for the treatment of attention deficit/hyperactivity disorder in both adults and children. However, it is also being examined for several off-label uses in adults including mood disorders, eating disorders, cognitive dysfunction, and the treatment of addictions. Prior to such use it is important to examine the reported adverse events to see if this represents an appropriate level of risk. This is particularly important in the light of recent warnings from several regulatory bodies about an increase in blood pressure in a significant percentage of patients taking atomoxetine. To understand the risks a literature review was performed, and which identified the following potential problems. The first is that this drug should not be given in patients with known cardiovascular problems, and that all adult patients who receive atomoxetine should be monitored for changes in blood pressure throughout treatment. Secondly, there are several clinical situations in which atomoxetine should be closely monitored, or avoided, including patients who have a history or risk of narrow angle glaucoma, epileptic seizures, Tourette's syndrome, a history of urinary outflow obstruction, or who are pregnant or lactating. In conclusion, the current literature suggests that atomoxetine can be safely used off-label provided the above precautions are taken.

The emerging role of norepinephrine in cognitive dysfunctions of Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder, affecting 1% of the population over age 60. In those patients cognitive dysfunction is a persistent issue that impairs quality of life and productivity. Neuropathological studies demonstrate significant damage in brain regions outside the nigral dopamine (DA) system, including early degeneration of locus coeruleus norepinephrine (LC-NE) neurons, yet discussion of PD and treatment focus has remained dopaminergic-based. Motor symptoms benefit from DA replacement for many years, but other symptoms including several cognitive deficits continue unabated. Recent interest in non-DA substrates of PD highlights early involvement of LC-NE neurons and provides evidence for a prodromal phase, with cognitive disturbance, even in sporadic PD. We outline insights from basic research in LC-NE function to clinical and pathological evidence highlighting a role for NE in PD cognitive dysfunction. We propose that loss of LC-NE regulation, particularly in higher cortical regions, critically underlies certain cognitive dysfunctions in early PD. As a major unmet need for patients, research and use of NE drugs in PD may provide significant benefits for cognitive processing.

Psychosis, apathy, depression and anxiety in Parkinson's disease

Psychiatric symptoms are important non-motor features in PD, which occur at high frequency and have significant impact on health related quality of life. This review concentrates on the prevalence, pathophysiology, diagnosis and treatment of depression, anxiety, apathy and psychosis. The pathophysiology of these disorders is complex, reflecting the widespread brainstem and cortical pathology in PD, with involvement of several neurotransmitters, including dopaminergic, serotonergic, noradrenergic and cholinergic systems. The diagnosis of psychiatric conditions, in particular affective disorders, is challenging because of the overlap of somatic features of psychiatric disorders and underlying movement disorder. The pathogenesis is likely to differ considerably from non-PD patients, and treatments used in general psychiatry services may not be as effective in PD and will require clearer clarification in well-designed clinical studies. Management strategies include adjustment of dopaminergic medication, use of psychotropic treatments and behavioural and psychological approaches. However, the future challenge will be to develop treatments developed specifically for the pathogenesis of these disorders in PD.

Parkinson's disease therapeutics: new developments and challenges since the introduction of levodopa

The demonstration that dopamine loss is the key pathological feature of Parkinson's disease (PD), and the subsequent introduction of levodopa have revolutionalized the field of PD therapeutics. This review will discuss the significant progress that has been made in the development of new pharmacological and surgical tools to treat PD motor symptoms since this major breakthrough in the 1960s. However, we will also highlight some of the challenges the field of PD therapeutics has been struggling with during the past decades. The lack of neuroprotective therapies and the limited treatment strategies for the nonmotor symptoms of the disease (ie, cognitive impairments, autonomic dysfunctions, psychiatric disorders, etc.) are among the most pressing issues to be addressed in the years to come. It appears that the combination of early PD nonmotor symptoms with imaging of the nigrostriatal dopaminergic system offers a promising path toward the identification of PD biomarkers, which, once characterized, will set the stage for efficient use of neuroprotective agents that could slow down and alter the course of the disease.

Depression in Parkinson disease--epidemiology, mechanisms and management

Depression occurs in around 35% of patients with Parkinson disease (PD) and is often persistent. Symptoms of depression can be evident in individuals at the time of diagnosis and might develop in the premotor stage of the disease. The underlying mechanisms of depression in PD are not known in detail, but changes in brain structure, signaling by neurotransmitters, and levels of inflammatory and neurotrophic factors are all suggested to contribute to its development. Psychosocial factors and pain could also have roles in depression. Changes in dopaminergic, noradrenergic and serotonergic systems in patients with PD might help to explain the incidence of depression in these individuals. Antidepressants that have dual serotonergic and noradrenergic effects are the drugs of choice for treating depression in PD. However, antiparkinsonian drugs might have beneficial effects not only on the motor symptoms of disease, but also on a patient's mood. Deep brain stimulation can worsen depression in some patients, but a preliminary study has suggested that transcranial magnetic stimulation could improve symptoms of depression. This Review describes the frequency and course of depression in patients with PD. The mechanisms that underlie depression in this disease are also discussed, and the management strategies for these patients are highlighted.

Frontostriatal cognitive staging in Parkinson's disease

Cognitive impairment and behavioural disorders are often encountered in subjects with Parkinson's disease (PD). A simple PD-related frontostriatal cognitive dysfunction (PDFCD) staging is proposed. Executive dysfunction and mental fatigue (stage I), depression/anxiety (stage IIa), apathy/pain (stage IIb), and dementia (stage III) reflect a sequential process of dopamine depletion occurring in different regions of the striatum (stages I and II) and the frontal cortex (stage III). In addition to these nonmotor manifestations present in the unmedicated (OFF) state, the PDFCD model also predicts a number of complications related to dopaminergic treatment (ON state), from impulse control disorders (stages I and IIa) to hallucinations (stage IIb) and psychosis (stage III). Although the model admittedly needs further refinements, it provides a framework for hypothesis testing and may help clinicians optimize therapeutic strategies.

Mild cognitive impairment in Parkinson's disease

Parkinson's disease (PD) traditionally has been defined by its characteristic motor hallmarks, but non-motor features such as cognitive impairment and dementia are increasingly recognized as part of PD. Mild cognitive impairment (MCI) is common in non-demented PD patients, occurring in about 20-50%. Frequency estimates and clinical features of mild cognitive impairment in PD (PD-MCI), however, vary across studies due to methodological differences and lack of uniform diagnostic criteria for PD-MCI. Overall, PD-MCI patients exhibit nonamnestic deficits in cognitive domains such as executive function, attention, and visuospatial function; however, the cognitive phenotype of PD-MCI is heterogeneous with some patients demonstrating greater amnestic deficits. PD-MCI patients, particularly those with posterior cortical profiles, may be at high risk for developing dementia. Various biomarkers studied in PD-MCI including cerebrospinal fluid, genetic analyses, and neuroimaging suggest that there may be distinct PD-MCI profiles. Future studies using uniform PD-MCI diagnostic criteria and incorporating biomarkers and longitudinal follow-up of PD-MCI cohorts are needed to understand PD-MCI as a transitional state between normal cognition and dementia.

Therapeutic potential of melatonin and its analogs in Parkinson's disease: focus on sleep and neuroprotection

Sleep disorders constitute major nonmotor features of Parkinson's disease (PD) that have a substantial effect on patients' quality of life and can be related to the progression of the neurodegenerative disease. They can also serve as preclinical markers for PD, as it is the case for rapid eye movement (REM)-associated sleep behavior disorder (RBD). Although the etiology of sleep disorders in PD remains undefined, the assessment of the components of the circadian system, including melatonin secretion, could give therapeutically valuable insight on their pathophysiopathology. Melatonin is a regulator of the sleep/wake cycle and also acts as an effective antioxidant and mitochondrial function protector. A reduction in the expression of melatonin MT(1) and MT(2) receptors has been documented in the substantia nigra of PD patients. The efficacy of melatonin for preventing neuronal cell death and for ameliorating PD symptoms has been demonstrated in animal models of PD employing neurotoxins. A small number of controlled trials indicate that melatonin is useful in treating disturbed sleep in PD, in particular RBD. Whether melatonin and the recently developed melatonergic agents (ramelteon, tasimelteon, agomelatine) have therapeutic potential in PD is also discussed.

Treatment of Apathy in Huntington's Disease and Other Movement Disorders

OPINION STATEMENT

Apathy is one of the most prevalent neurobehavioral symptoms in Huntington's disease (HD), occurring in approximately 70% of the symptomatic HD population. Apathy scores in patients with HD are highly correlated with duration of illness, suggesting that apathy is an inevitable consequence of advanced disease. Although less distressing than symptoms like depression and less disruptive than irritability or aggression, apathy has a considerable adverse impact on those affected with HD because it leads to a decrease of the goal-directed behaviors that contribute much to the day-to-day quality of life. As a neuropsychiatric syndrome, apathy is also common in patients with other neuropsychiatric disorders such as Parkinson's disease, traumatic brain injury, cerebrovascular accident, dementia, and other neurodegenerative conditions. The nosologic status of apathy and lack of a clear definition has probably contributed to the paucity of therapeutic evidence in this area. Several different scales are available to measure apathy, including the Apathy Evaluation Scale, Apathy Inventory, Lilles Apathy Rating Scale, and the apathy items from the Unified HD Rating Scale, the Problem Behaviours Assessment for HD, and the Neuropsychiatric Inventory, but all are based on slightly different definitions of apathy, so the scores obtained may not be directly comparable. Assessment may also be complicated by overlap between the manifestations of apathy and other complications of HD such as depression, so the identification and treatment of these comorbid conditions is important. No adequate evidence currently supports any specific pharmacologic or psychological intervention for apathy in HD. Evidence can only be extrapolated from interventional studies done in other basal ganglia disorders such as Parkinson's disease or other neurodegenerative disorders such as dementia. The neurobiology of apathy points towards three areas of functional connectivity: connections between the dorsolateral prefrontal cortex (PFC) and basal ganglia, orbitomedial PFC and basal ganglia, and dorsomedial PFC and basal ganglia. Pharmacologic interventions such as cholinesterase inhibitors, the dopaminergic antidepressant bupropion, amantadine, levodopa, bromocriptine, methylphenidate, and atypical antipsychotics have all been tried in other neurodegenerative disorders, but not in HD. Psychosocial interventions such as cognitive stimulation therapy and multisensory stimulation, which have been used in patients with dementia, have not been properly studied in HD. Individualized treatment should be considered, using a combination of methods, as there is no evidence to support one particular type of treatment. Multidisciplinary input, environmental modifications, improved psychosocial support, and psychoeducation programs designed to help caregivers to understand and compensate for the deficits caused by this symptom may all have a role to play in the treatment of apathy.

Mild cognitive impairment in Parkinson's disease

Prospective studies conducted during the last decade have shown that the majority of patients with Parkinson's disease (PD) develop dementia. In addition, using a variety of definitions and methods, more recent research suggests that approximately a quarter of PD patients without dementia have mild cognitive impairment (PD-MCI). Furthermore, several studies have shown that approximately 20% have MCI even at time of diagnosis of PD. The typical cognitive deficits include visuospatial, attentional, and executive deficits, but memory deficits have also been shown. The etiology of PD-MCI is not known, but it is likely that mechanisms known to contribute to dementia in PD (ie, limbic and cortical Lewy bodies, amyloid plaques, and cholinergic deficits) play a role, in addition to dysfunction of dopaminergic frontostriatal circuits. PD-MCI predicts a shorter time to dementia, and preliminary evidence suggests that this is particularly true for posterior cognitive deficits. There are currently no systematic clinical trials in PD-MCI.

The Movement Disorder Society Evidence-Based Medicine Review Update: Treatments for the non-motor symptoms of Parkinson's disease

The Movement Disorder Society (MDS) Task Force on Evidence-Based Medicine (EBM) Review of Treatments for Parkinson's Disease (PD) was first published in 2002 and was updated in 2005 to cover clinical trial data up to January 2004 with the focus on motor symptoms of PD. In this revised version the MDS task force decided it was necessary to extend the review to non-motor symptoms. The objective of this work was to update previous EBM reviews on treatments for PD with a focus on non-motor symptoms. Level-I (randomized controlled trial, RCT) reports of pharmacological and nonpharmacological interventions for the non-motor symptoms of PD, published as full articles in English between January 2002 and December 2010 were reviewed. Criteria for inclusion and ranking followed the original program outline and adhered to EBM methodology. For efficacy conclusions, treatments were designated: efficacious, likely efficacious, unlikely efficacious, non-efficacious, or insufficient evidence. Safety data were catalogued and reviewed. Based on the combined efficacy and safety assessment, Implications for clinical practice were determined using the following designations: clinically useful, possibly useful, investigational, unlikely useful, and not useful. Fifty-four new studies qualified for efficacy review while several other studies covered safety issues. Updated and new efficacy conclusions were made for all indications. The treatments that are efficacious for the management of the different non-motor symptoms are as follows: pramipexole for the treatment of depressive symptoms, clozapine for the treatment of psychosis, rivastigmine for the treatment of dementia, and botulinum toxin A (BTX-A) and BTX-B as well as glycopyrrolate for the treatment of sialorrhea. The practical implications for these treatments, except for glycopyrrolate, are that they are clinically useful. Since there is insufficient evidence of glycopyrrolate for the treatment of sialorrhea exceeding 1 week, the practice implication is that it is possibly useful. The treatments that are likely efficacious for the management of the different non-motor symptoms are as follows: the tricyclic antidepressants nortriptyline and desipramine for the treatment of depression or depressive symptoms and macrogol for the treatment of constipation. The practice implications for these treatments are possibly useful. For most of the other interventions there is insufficient evidence to make adequate conclusions on their efficacy. This includes the tricyclic antidepressant amitriptyline, all selective serotonin reuptake inhibitors (SSRIs) reviewed (paroxetine, citalopram, sertraline, and fluoxetine), the newer antidepressants atomoxetine and nefazodone, pergolide, Ω-3 fatty acids as well as repetitive transcranial magnetic stimulation (rTMS) for the treatment of depression or depressive symptoms; methylphenidate and modafinil for the treatment of fatigue; amantadine for the treatment of pathological gambling; donepezil, galantamine, and memantine for the treatment of dementia; quetiapine for the treatment of psychosis; fludrocortisone and domperidone for the treatment of orthostatic hypotension; sildenafil for the treatment of erectile dysfunction, ipratropium bromide spray for the treatment of sialorrhea; levodopa/carbidopa controlled release (CR), pergolide, eszopiclone, melatonin 3 to 5 mg and melatonin 50 mg for the treatment of insomnia and modafinil for the treatment of excessive daytime sleepiness. Due to safety issues the practice implication is that pergolide and nefazodone are not useful for the above-mentioned indications. Due to safety issues, olanzapine remains not useful for the treatment of psychosis. As none of the studies exceeded a duration of 6 months, the recommendations given are for the short-term management of the different non-motor symptoms. There were no RCTs that met inclusion criteria for the treatment of anxiety disorders, apathy, medication-related impulse control disorders and related behaviors other than pathological gambling, rapid eye movement (REM) sleep behavior disorder (RBD), sweating, or urinary dysfunction. Therefore, there is insufficient evidence for the treatment of these indications. This EBM review of interventions for the non-motor symptoms of PD updates the field, but, because several RCTs are ongoing, a continual updating process is needed. Several interventions and indications still lack good quality evidence, and these gaps offer an opportunity for ongoing research. © 2011 Movement Disorder Society.

Serotonin-dependent depression in Parkinson's disease: a role for the subthalamic nucleus?

Depression is the most common neuropsychiatric co-morbidity in Parkinson's disease (PD). The underlying mechanism of depression in PD is complex and likely involves biological, psychosocial and therapeutic factors. The biological mechanism may involve changes in monoamine systems, in particular the serotonergic (5-hydroxytryptamine, 5-HT) system. It is well established that the 5-HT system is markedly affected in the Parkinsonian brain, with evidence including pathological loss of markers of 5-HT axons as well as cell bodies in the dorsal and median raphe nuclei of the midbrain. However, it remains unresolved whether alterations to the 5-HT system alone are sufficient to confer vulnerability to depression. Here we propose low 5-HT combined with altered network activity within the basal ganglia as critically involved in depression in PD. The latter hypothesis is derived from a number of recent findings that highlight the close interaction between the basal ganglia and the 5-HT system, not only in motor but also limbic functions. These findings include evidence that clinical depression is a side effect of deep brain stimulation (DBS) of the subthalamic nucleus (STN), a treatment option in advanced PD. Further, it has recently been demonstrated that STN DBS in animal models inhibits 5-HT neurotransmission, and that this change may underpin depressive-like side effects. This review provides an overview of 5-HT alterations in PD and a discussion of how these changes might combine with altered basal ganglia network activity to increase depression vulnerability.

Cognitive impairment in nondemented Parkinson's disease

A substantial percentage of patients with newly diagnosed Parkinson's disease without dementia are reported to be affected by cognitive impairment (CI). In practice, however, CI is underrecognized, as the signs may not be apparent in early-stage disease and many routine assessment tools lack the sensitivity to detect subtle cognitive dysfunction. Patients with PD and mild CI (MCI) may have a higher risk of developing dementia than cognitively intact PD patients; however, it is not currently known which patients with CI are at increased risk of developing dementia. This review summarizes current knowledge about CI in nondemented PD; it discusses the structural and functional changes associated with CI and addresses areas of unmet needs. We focus on questions that should be addressed in future studies to achieve consensus on its characteristics and definition, pathophysiology, epidemiology, diagnosis and assessment, and treatment and management.

Apathy and Parkinson's disease

OPINION STATEMENT

Apathy, a frequent finding in Parkinson's disease (PD), is significantly associated with depression and dementia. Few studies have examined the efficacy of psychotropic or psychological treatments of apathy in PD, and adequate randomized controlled trials are still lacking. There is anecdotal evidence that dopaminergic agonists may be a useful treatment modality. Levodopa may improve the loss of motivation in the "off" motor state, and dopaminergic agonists could be useful to treat apathy after the withdrawal of dopaminergic treatment in patients undergoing deep brain stimulation of the subthalamic nucleus. On the other hand, the selective norepinephrine reuptake inhibitor atomoxetine did not demonstrate efficacy in improving apathy in a randomized controlled trial with apathy as a secondary efficacy measure. Given the significant association between apathy and both depression and cognitive decline, future studies should examine whether improving mood and cognition may also have a positive impact upon apathy in PD. For those PD patients with "pure" apathy, specific psychotherapeutic techniques should be developed.

Noradrenaline and Parkinson's disease

Parkinson's disease (PD) is characterized by the degeneration of dopamine (DA) neurons in the substantia nigra pars compacta, and motor symptoms including bradykinesia, rigidity, and tremor at rest. These symptoms are exhibited when striatal dopamine concentration has decreased by around 70%. In addition to motor deficits, PD is also characterized by the non-motor symptoms. However, depletion of DA alone in animal models has failed to simultaneously elicit both the motor and non-motor deficits of PD, possibly because the disease is a multi-system disorder that features a profound loss in other neurotransmitter systems. There is growing evidence that additional loss of noradrenaline (NA) neurons of the locus coeruleus, the principal source of NA in the brain, could be involved in the clinical expression of motor as well as in non-motor deficits. In the present review, we analyze the latest evidence for the implication of NA in the pathophysiology of PD obtained from animal models of parkinsonism and from parkinsonian patients. Recent studies have shown that NA depletion alone, or combined with DA depletion, results in motor as well as in non-motor dysfunctions. In addition, by using selective agonists and antagonists of noradrenaline alpha receptors we, and others, have shown that α2 receptors are implicated in the control of motor activity and that α2 receptor antagonists can improve PD motor symptoms as well as l-Dopa-induced dyskinesia. In this review we argue that the loss of NA neurons in PD has an impact on all PD symptoms and that the addition of NAergic agents to dopaminergic medication could be beneficial in the treatment of the disease.

Neurobiology of depression and anxiety in Parkinson's disease

Depression and anxiety are common in Parkinson's disease (PD) and have important consequences on quality of life. These have long been recognized as frequent accompanying syndromes of PD, and several reports suggest that these are the causative process or risk factors that are present many years before the appearance of motor symptoms. The neurochemical changes in PD involving dopamine, norepinephrine, and serotonin might be related to the pathophysiology of depression and anxiety, but this is still not clear. Several studies showed that anxiety in PD patients occurs earlier than depression, during premotor phase, suggesting that there may be a link between the mechanisms that cause anxiety and PD. Whereas a recent study reported that PD patients with depression and anxiety were associated with different demographic and clinical features.

A précis of recent advances in the neuropsychology of mild cognitive impairment(s) in Parkinson's disease and a proposal of preliminary research criteria

Cognitive changes of Parkinson's disease (PD) manifest earlier and are more heterogeneous than previously appreciated. Approximately one-third of patients have at least mild cognitive changes at PD diagnosis, and subtle changes might be appreciable among those at risk for PD. Executive dysfunction is the most common cognitive change, but other phenotypes exist. Pathobiologic and potential prognostic differences among cognitive phenotypes remain poorly understood. Progress in the neuropsychology, epidemiology and pathobiology of mild cognitive impairment (MCI) in PD is hampered by lack of diagnostic criteria. This study proposes preliminary research criteria for two categories of PD non-dementia cognitive impairment.

Parkinson's disease: the quintessential neuropsychiatric disorder

Although diagnosed by characteristic motor features, Parkinson's disease may be preceded, and is frequently accompanied by, a wide range of cognitive and neuropsychiatric features. In addition to the most commonly studied disorders of dementia, depression, and psychosis, other relatively common and clinically significant psychiatric complications include impulse control disorders, anxiety symptoms, disorders of sleep and wakefulness, and apathy. These problems may be underrecognized and are frequently undertreated. The emergent focus on nonmotor aspects of Parkinson's disease over the past quarter of a century is highlighted by a nonlinear increase in the number of articles published devoted to this topic. Although the development of newer antidepressants, atypical antipsychotics, and cholinesterase inhibitors in recent years has had a positive benefit on the management of these troublesome and distressing symptoms, responses are frequently suboptimal, and this remains an area of major unmet therapeutic need.