Physostigmine treatment of progressive supranuclear palsy

Diagnostic Efficacy and Clinical Relevance of Artificial Intelligence in Detecting Cognitive Decline

Cognitive impairment is an age-associated disorder of increasing prevalence as the aging population continues to grow. Classified based on the level of cognitive decline, memory, function, and capacity to conduct activities of daily living, cognitive impairment ranges from mild cognitive impairment to dementia. When considering the insidious nature of the etiologies responsible for varying degrees of cognitive impairment, early diagnosis may provide a clinical benefit through the facilitation of early treatment. Typical diagnosis relies heavily on evaluation in a primary care setting. However, there is evidence that other diagnostic tools may aid in an earlier diagnosis of the different underlying pathologies responsible for cognitive impairment. Artificial intelligence represents a new intersecting field with healthcare that may aid in the early detection of neurodegenerative disorders. When assessing the role of AI in detecting cognitive decline, it is important to consider both the diagnostic efficacy of AI algorithms and the clinical relevance and impact of early interventions as a result of early detection. Thus, this review highlights promising investigations and developments in the space of artificial intelligence and healthcare and their potential to impact patient outcomes.

Reduction in Volume of Nucleus Basalis of Meynert Is Specific to Parkinson’s Disease and Progressive Supranuclear Palsy but Not to Multiple System Atrophy

Objectives

To study in vivo gray matter (GM) volumes of the nucleus basalis of Meynert (nbM) in different parkinsonian syndromes and assess their relationship with clinical variables.

Methods

T1-weighted magnetic resonance images from patients with progressive supranuclear palsy (PSP, N = 43), multiple system atrophy (MSA, N = 23), Parkinson’s disease (PD, N = 26), and healthy controls (HC, N = 29) were included. T1-weighted images were analyzed using a voxel-based morphometry approach implemented in the VBM8 toolbox, and nbM volumes were extracted from the spatially normalized GM images using a cyto-architectonically-defined nbM mask in stereotactic standard space. NbM volumes were compared between groups, while controlling for intracranial volume. Further, within each group correlation analyses between nbM volumes and the Mini Mental Status Examination (MMSE), Hoehn and Yahr stage, PSP Rating Scale, Unified Parkinson’s Disease Rating Scale part III and Frontal Assessment Battery scores were performed.

Results

Significantly lower nbM volumes in patients with PSP and PD compared to HC or patients with MSA were found. No significant correlations between MMSE and nbM volumes were detected in any of the subgroups. No significant correlations were found between clinical scores and nbM volumes in PSP or other groups.

Conclusion

nbM volumes were reduced both in PD and PSP but not in MSA. The lack of significant correlations between nbM and cognitive measures suggests that other factors, such as frontal atrophy, may play a more important role than subcortical cholinergic atrophy in PSP patients. These results may indicate that other drug-targets are needed to improve cognitive function in PSP patients.

Treatment of frontotemporal dementia

OPINION STATEMENT

Frontotemporal dementia (FTD) encompasses a spectrum of neurodegenerative diseases with heterogeneous clinical presentations and two predominant types of underlying neuropathology. FTD typically comprises three distinct clinical syndromes: behavioral variant frontotemporal dementia (bvFTD), semantic variant primary progressive aphasia (svPPA), and nonfluent variant primary progressive aphasia (nfvPPA). FTD also frequently overlaps both clinically and neuropathologically with three other neurodegenerative syndromes: corticobasal syndrome (CBS), progressive supranuclear palsy (PSP), and amyotrophic lateral sclerosis (ALS). Each syndrome can be associated with one or more underlying neuropathological diagnoses and are referred to as frontotemporal lobar degeneration (FTLD). Although the various FTD syndromes can substantially differ in terms of clinical symptoms and underlying pathology, the symptoms can be broadly categorized into behavioral, cognitive and motor domains. Currently there are no Food and Drug Administration (FDA) approved therapies for the above syndromes except riluzole for ALS. FTD treatment strategies generally rely on off-label use of medications for symptomatic management, and most therapies lack quality evidence from randomized, placebo-controlled clinical trials. For behavioral symptoms, selective serotonin reuptake inhibitors may be effective, while case reports hint at possible efficacy with antipsychotics or anti-epileptics, but use of these latter agents is limited due to concerns regarding side effects. There are no effective therapies for cognitive complaints in FTD, which frequently involve executive function, memory, and language. Motor difficulties associated with FTD may present with parkinsonian symptoms or motor neuron disease, for which riluzole is indicated as therapy. Compared to idiopathic Parkinson's disease, FTD-related atypical parkinsonism is generally not responsive to dopamine replacement therapies, but a small percentage of patients may experience improvement with a trial of carbidopa-levodopa. Physical and occupational therapy remain an important corner stone of motor symptom management in FTD. Speech therapy may also help patients manage symptoms associated with aphasia, apraxia, and dysarthria. Recent advances in the understanding of FTLD pathophysiology and genetics have led to development of potentially disease-modifying therapies as well as symptomatic therapies aimed at ameliorating social and behavioral deficits.

Clinical trials: past, current, and future for atypical Parkinsonian syndromes

There are currently no effective Food and Drug Administration-approved treatments for atypical parkinsonian disorders such as progressive supranuclear palsy, corticobasal degeneration, dementia with Lewy bodies, or multiple system atrophy. Previous treatment trials for these disorders were focused on symptomatic support and did not affect disease progression. Recent breakthroughs in neuropathology and pathophysiology have allowed a new understanding of these disorders and investigation into potentially disease modifying therapies. Randomized, placebo-controlled clinical trials of these disorders will be reviewed here. Suggestions for future therapeutic targets and clinical trial design (with a focus on progressive supranuclear palsy) will also be provided.

Davunetide in patients with progressive supranuclear palsy: a randomised, double-blind, placebo-controlled phase 2/3 trial

BACKGROUND

In preclinical studies, davunetide promoted microtubule stability and reduced tau phosphorylation. Because progressive supranuclear palsy (PSP) is linked to tau pathology, davunetide could be a treatment for PSP. We assessed the safety and efficacy of davunetide in patients with PSP.

METHODS

In a double-blind, parallel group, phase 2/3 trial, participants were randomly assigned with permuted blocks in a 1:1 ratio to davunetide (30 mg twice daily, intranasally) or placebo for 52 weeks at 48 centres in Australia, Canada, France, Germany, the UK, and the USA. Participants met the modified Neuroprotection and Natural History in Parkinson Plus Syndrome study criteria for PSP. Primary endpoints were the change from baseline in PSP Rating Scale (PSPRS) and Schwab and England Activities of Daily Living (SEADL) scale at up to 52 weeks. All participants and study personnel were masked to treatment assignment. Analysis was by intention to treat. The trial is registered with Clinicaltrials.gov, number NCT01110720.

FINDINGS

313 participants were randomly assigned to davunetide (n=157) or to placebo (n=156), and 241 (77%) completed the study (118 and 156 in the davunetide and placebo groups, respectively). There were no differences in the davunetide and placebo groups in the baseline PSPRS and SEADL. The davunetide and placebo groups did not differ in the change from baseline in PSPRS (median 11·8 [95% CI 10·5 to 13·0] vs 11·8 [10·5 to 13·0], respectively, p=0·41) or SEADL (-0·20 [-0·20 to -0·17] vs -0·20 [-0·22 to -0·17], respectively, p=0·92). 54 serious adverse events were reported in each of the treatment groups, including 11 deaths in the davunetide group and ten in the placebo group. The frequency of nasal adverse events was greater in the davunetide group than in the placebo group (epistaxis 18 [12%] of 156 vs 13 [8%] of 156, rhinorrhoea 15 [10%] vs eight [5%], and nasal discomfort 15 [10%] vs one [<1%]).

INTERPRETATION

Davunetide is not an effective treatment for PSP. Clinical trials of disease-modifying treatment are feasible in patients with PSP and should be pursued with other promising tau-directed treatments.

FUNDING

Allon Therapeutics.

Cholinergic imaging in corticobasal syndrome, progressive supranuclear palsy and frontotemporal dementia

Corticobasal syndrome, progressive supranuclear palsy and frontotemporal dementia are all part of a disease spectrum that includes common cognitive impairment and movement disorders. The aim of this study was to characterize brain cholinergic deficits in these disorders. We measured brain acetylcholinesterase activity by [11C] N-methylpiperidin-4-yl acetate and positron emission tomography in seven patients with corticobasal syndrome (67.6+/-5.9 years), 12 with progressive supranuclear palsy (68.5+/-4.1 years), eight with frontotemporal dementia (59.8+/-6.9 years) and 16 healthy controls (61.2+/-8.5 years). Two-tissue compartment three-parameter model and non-linear least squares analysis with arterial input function were performed. k3 value, an index of acetylcholinesterase activity, was calculated voxel-by-voxel in the brain of each subject. The k3 images in each disease group were compared with the control group by using Statistical Parametric Mapping 2. Volume of interest analysis was performed on spatially normalized k3 images. The corticobasal syndrome group showed decreased acetylcholinesterase activity (k3 values) in the paracentral region, frontal, parietal and occipital cortices (P<0.05, cluster corrected). The group with progressive supranuclear palsy had reduced acetylcholinesterase activity in the paracentral region and thalamus (P<0.05, cluster corrected). The frontotemporal dementia group showed no significant differences in acetylcholinesterase activity. Volume of interest analysis showed mean cortical acetylcholinesterase activity to be reduced by 17.5% in corticobasal syndrome (P<0.001), 9.4% in progressive supranuclear palsy (P<0.05) and 4.4% in frontotemporal dementia (non-significant), when compared with the control group. Thalamic acetylcholinesterase activity was reduced by 6.4% in corticobasal syndrome (non-significant), 24.0% in progressive supranuclear palsy (P<0.03) and increased by 3.3% in frontotemporal dementia (non-significant). Both corticobasal syndrome and progressive supranuclear palsy showed brain cholinergic deficits, but their distribution differed somewhat. Significant brain cholinergic deficits were not seen in frontotemporal dementia, which may explain the unresponsiveness of this condition to cholinergic modulation therapy.

Behandlung der Demenz bei Parkinson-Syndromen

In parkinsonian syndromes dementia frequently occurs in the disease progress. The cholinergic system has been proposed as playing a key role in cognitive disturbances. Therefore the application of cholinesterase inhibitors (ChEI) is also hotly argued for dementia associated with parkinsonian syndromes. This review focuses on the specific symptoms of dementia in Parkinson's disease (PDD), dementia with Lewy bodies (DLB), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD). The effect of cholinergic treatment on cognition and behaviour is reported and critically discussed. There is evidence that medication with some ChEIs reduces cognitive disturbances and to a lesser extent improves activities of daily living in PDD. Behavioural symptoms also seem to be positively influenced by treatment with ChEIs in both PDD and DLB. The effect of treatment with cholinesterase inhibitors in PSP and CBD warrants more carefully designed studies including sufficient numbers of patients.

Treatment of dementia in parkinsonian syndromes with cholinesterase inhibitors

In Parkinsonian syndromes behavioural symptoms and dementia can be even more debilitating than motor symptoms and are an important predictor for nursing home placement and mortality. Neuropathologically, dementia seems to be primarily related to cortical changes rather than to subcortical alterations. Concerning neurotransmitter systems, the cholinergic system has been proposed to play a key role in cognitive disturbances. Based on studies with patients with Alzheimer disease, the application of cholinesterase inhibitors is vividly discussed also for dementia associated with parkinsonian syndromes. This review focuses on the specific symptoms of dementia in different parkinsonian syndromes and critically questions the effect of cholinergic treatment on cognitive functions in patients with extrapyramidal syndromes and dementia. There is evidence that medication with some cholinesterase inhibitors can enhance cognition as well as activities of daily living in dementia with Parkinson's disease and seems to reduce behavioural disturbances in both dementia with Parkinson's disease and dementia with Lewy bodies. The effect of treatment with cholinesterase inhibitors in progressive supranuclear palsy and corticobasal degeneration warrants carefully designed studies including a sufficient number of patients and symptom-adopted dementia scales.

Current and future treatments in progressive supranuclear palsy

Progressive supranuclear palsy (PSP) is an atypical parkinsonian disorder that, in spite of its growing recognition, is still underdiagnosed. For management, prognosis, and research, an accurate and early diagnosis is essential. PSP is a relentlessly progressive neurodegenerative disorder, clinically characterized by parkinsonism with prominent axial involvement and postural instability, bulbar symptoms, supranuclear ophthalmoplegia, and executive dysfunction. Abnormal neuronal and glial four-repeat tau aggregations affecting the basal ganglia and selective brainstem structures result in dysfunction of the five frontosubcortical circuits and brainstem functions. Primary therapeutic approaches are based on neurotransmitter replacement and palliative strategies. This article reviews the experience and challenges with neurotransmitter replacement and palliative strategies through an extensive literature search of studies published between 1965 and 2005. The role of and limited experience with alternative therapies, such as deep brain stimulation and pallidotomy, are also discussed. Advances in the development of biological therapies for PSP and a better understanding of its etiopathogenesis will likely result from epidemiologic studies and developed four-repeat tau-transgenic animal models. The management of patients with this disorder poses a considerable challenge and includes symptomatic and palliative strategies, as well as education and support, to improve the quality of life for patients and their caregivers.

Toward future therapies in progressive supranuclear palsy

There is a stern therapeutic challenge for progressive supranuclear palsy (PSP) that has not yet been met. The lack of randomized, controlled trials and negative outcomes from the vast majority of studies make it impossible to set therapeutic standards, or to give clear recommendations. We review progress to date in this area and briefly consider future potential therapeutic strategies.

Treatment of progressive supranuclear palsy and corticobasal degeneration

Success in treating patients with progressive supranuclear palsy and corticobasal degeneration remains exceedingly low. This finding probably relates to the widespread distribution of the pathological changes that account for the varied and complex spectrum of clinical manifestations. Dopaminergic drugs are regularly used for the parkinsonian features; however, these rarely result in more than modest benefit, and when better or sustained responses are obtained, as sometimes occurs in progressive supranuclear palsy, the clinical features are atypical and diagnosis is often delayed or not made in life. A variety of other treatments have been used in both disorders, sometimes directed at other specific features such as dystonia or myoclonus, and these treatments will be reviewed. Greater success in treating these disorders will require advances in our understanding of their cause(s) or the pathogenetic mechanisms underlying the neurodegenerative processes. The similarities in the molecular pathology of these four-repeat tauopathies suggests that important advances in the management of one will have a definite impact on the treatment of the other.

Progressive supranuclear palsy: clinical features, pathophysiology and management

Progressive supranuclear palsy (PSP) is a degenerative condition of unknown aetiology that produces an akinetic-rigid form of parkinsonism characterised by early falls and abnormalities of extraocular movements. Mean age of onset is approximately 63 years, and mean survival from symptom onset is 9 years. Men are much more frequently affected than women. The classic clinical finding is supranuclear ophthalmoplegia, which may not present until late in the illness, if at all. The clinical diagnosis of PSP can be difficult to make, as the sites of pathology are heterogeneous. Structural and functional neuroimaging studies, although not specific for PSP, may be of some assistance in making the diagnosis. The definitive diagnosis of PSP requires the presence of both clinical and neuropathological evidence. Multiple anatomical sites are affected in PSP. The most consistently involved are the subthalamic nucleus, globus pallidus interna and externa, pontine nuclei, periaqueductal grey matter and the substantia nigra. The location of the pathology accounts for the clinical features. The histological hallmark of PSP is the presence of globose neurofibrillary tangles in the affected subcortical nuclei. Neurofibrillary tangles are composed of abnormally phosphorylated tau, a microtubule-associated protein that is involved in maintenance of the cytoskeleton. Abnormalities near or in the gene coding for tau are implicated in the pathogenesis of PSP. The multiple neurotransmitter abnormalities, including those affecting dopamine, acetylcholine, gamma-aminobutyric acid and norepinephrine (noradrenaline) systems and pathways, as well as both pre- and post-synaptic pathology, make pharmacological therapy of PSP a challenge. Although an individual patient may respond to a drug, in general patients with PSP have a minimal response and a short duration of sustained benefit.

Donepezil in the treatment of progressive supranuclear palsy

OBJECTIVES

To evaluate the effect of 3 month therapy with donepezil, a centrally acting cholinesterase inhibitor, on cognitive performances, motor function and daily living activities in progressive supranuclear palsy (PSP).

MATERIALS AND METHODS

Six patients with a diagnosis of PSP were evaluated at baseline and after 3 months of treatment with donepezil, 10 mg given at bedtime. Cognitive functions, motor symptoms and daily activities were evaluated by means of appropriate rating scales.

RESULTS

Donepezil was not effective on cognitive dysfunction and did not change ratings of daily living. Parkinsonian symptoms were unaffected by donepezil treatment.

CONCLUSIONS

Cholinergic replacement therapy alone is not likely to improve symptoms in a disorder characterized by a more widespread impairment of monoaminergic systems. Larger studies may be necessary to confirm the lack of effect of donepezil in this disorder.

Progressive supranuclear palsy (Steele-Richardson-Olszewski disease)

Progressive supranuclear palsy is a neurodegenerative disease which affects the brainstem and basal ganglia. Patients present with disturbance of balance, a disorder of downward gaze and L-DOPA-unresponsive parkinsonism and usually develop progressive dysphagia and dysarthria leading to death from the complications of immobility and aspiration. Treatment remains largely supportive but, potentially, treatments based on cholinergic therapy may be useful. As in Alzheimer's disease, the neuronal degeneration is associated with the deposition of hyperphosphorylated tau protein as neurofibrillary tangles but there are important distinctions between the two diseases. Evidence from familial fronto-temporal dementia with parkinsonism linked to chromosome 17 suggests that tau protein deposition is a primary pathogenic event in some neurodegenerative diseases. The understanding of the mechanism of tau deposition in progressive supranuclear palsy is likely to be of importance in unravelling its aetiology.

Progressive supranuclear palsy

Richardson observed an unusual clinical syndrome in the 1950s, which he later designated progressive supranuclear palsy (PSP). Over the past 25 years, although knowledge of this disorder has gradually improved, its cause is still unknown, pathogenesis is unclear, and there is still no definitive treatment for this disorder. This article reviews the epidemiology, clinical features, diagnostic criteria, neuropathology, neuroimaging, and treatment of PSP.

Pharmacological evaluation of the cholinergic system in progressive supranuclear palsy

Severe cholinergic loss occurs in the brains of patients with progressive supranuclear palsy. To evaluate the functional implications of this neuronal deficit, dose-response curves were obtained in patients with progressive supranuclear palsy and normal control subjects undergoing intravenous cholinergic blockade (scopolamine) and stimulation (physostigmine). Physostigmine had no significant neurobehavioral effects at any dose in patients with progressive supranuclear palsy. Scopolamine, at low and medium doses, significantly impaired memory performance of both groups, but worsened the gait of only the patients. High-dose scopolamine, which could not be tolerated by the patients, resulted in gait deterioration among control subjects. Thus, patients with progressive supranuclear palsy have increased sensitivity to cholinergic blockade compared to control subjects. Since loss of cholinergic neurons appears to contribute to the pathogenesis of certain cognitive and motor deficits found in progressive supranuclear palsy, the use of oral anticholinergics should ordinarily be avoided in this disorder. On the other hand, physostigmine at clinically tolerated dose levels seems to be therapeutically ineffective.

Cholinergic approaches to the treatment of progressive supranuclear palsy

In spite of the severe loss of cholinergic neurons in the brains of patients with progressive supranuclear palsy (PSP), marginal or null benefits are seen in clinical trials after the administration of physostigmine, a cholinesterase inhibitor, or RS-86, a cholinergic agonist. The possible role of cholinergic therapy in PSP is reevaluated.

Therapy for progressive supranuclear palsy: past and future

Dysfunction of multiple brain systems in progressive supranuclear palsy (PSP) has complicated attempts to treat the disease. Neurotransmitter replacement strategies targeting the dopaminergic, cholinergic, and serotonergic systems have been unsuccessful. In order to bypass the degenerated cortico-striato-pallidal loop, we administered the adrenergic agonist idazoxan (IDA) to treat PSP in two randomized double-blind, placebo controlled, crossover studies. Approximately one half of patients enrolled in these studies showed statistically significant improvement in balance and manual dexterity while taking IDA compared to placebo. These results suggest that new therapies that target structures outside of the basal ganglia may be useful for symptomatic treatment of PSP. Applying this strategy and developing treatments that arrest or reverse clinical deterioration in PSP will require improved understanding of the process underlying the illness.

CSF galanin and neuropeptide Y immunoreactivity in progressive supranuclear palsy

Progressive supranuclear palsy (PSP) has been associated with degenerative changes in cholinergic and dopaminergic neurons in several brain regions. Since acetylcholine is colocalized with the neuropeptide galanin in certain neuronal populations, we measured the concentration of this neuropeptide and neuropeptide Y in cerebrospinal fluid (CSF) of 11 patients with PSP and in 16 age-matched healthy controls. No significant alterations in the CSF levels of galanin or neuropeptide Y were found.

Cerebrospinal fluid acetylcholinesterase in progressive supranuclear palsy: reduced activity relative to normal subjects and lack of inhibition by oral physostigmine

Acetylcholinesterase (AChE) activity was measured in lumbar cerebrospinal fluid (CSF) of 11 patients with progressive supranuclear palsy (PSP) and 18 age-matched healthy control subjects. Mean CSF AChE activity in PSP subjects was significantly reduced by 31% relative to control subjects (p less than 0.002). In the light of evidence of a central cholinergic deficit, physostigmine was administered orally (0.5-2.0 mg every two hours, six times a day for 10 days) to eight of the 11 PSP patients. CSF was sampled when the patients were on placebo and when receiving physostigmine and CSF AChE and butyrylcholinesterase (BChE) activities were measured. There was no significant change in either CSF AChE or BChE activities following physostigmine treatment. These data suggest that the doses of physostigmine used were insufficient to produce marked inhibition of AChE within the central nervous system.