Awareness of memory deficits in early stage Huntington's disease

The effect of Huntington's disease on cognitive and physical motivation

Apathy is one of the most common neuropsychiatric features of Huntington's disease. A hallmark of apathy is diminished goal-directed behaviour, which is characterized by a lower motivation to engage in cognitively or physically effortful actions. However, it remains unclear whether this reduction in goal-directed behaviour is driven primarily by a motivational deficit and/or is secondary to the progressive cognitive and physical deficits that accompany more advanced disease. We addressed this question by testing 17 individuals with manifest Huntington's disease and 22 age-matched controls on an effort-based decision-making paradigm. Participants were first trained on separate cognitively and physically effortful tasks and provided explicit feedback about their performance. Next, they chose on separate trials how much effort they were willing to exert in each domain in return for varying reward. At the conclusion of the experiment, participants were asked to rate their subjective perception of task load. In the cognitive task, the Huntington's disease group were more averse to cognitive effort than controls. Although the Huntington's disease group were more impaired than controls on the task itself, their greater aversion to cognitive effort persisted even after controlling for task performance. This suggests that the lower levels of cognitive motivation in the Huntington's disease group relative to controls was most likely driven by a primary motivational deficit. In contrast, both groups expressed a similar preference for physical effort. Importantly, the similar levels of physical motivation across both groups occurred even though participants with Huntington's disease performed objectively worse than controls on the physical effort task, and were aware of their performance through explicit feedback on each trial. This indicates that the seemingly preserved level of physical motivation in Huntington's disease was driven by a willingness to engage in physically effortful actions despite a reduced capacity to do so. Finally, the Huntington's disease group provided higher ratings of subjective task demand than controls for the cognitive (but not physical) effort task and when assessing the mental (but not the physical) load of each task. Together, these results revealed a dissociation in cognitive and physical motivation deficits between Huntington's disease and controls, which were accompanied by differences in how effort was subjectively perceived by the two groups. This highlights that motivation is the final manifestation of a complex set of mechanisms involved in effort processing, which are separable across different domains of behaviour. These findings have important clinical implications for the day-to-day management of apathy in Huntington's disease.

Influence of anosognosia on patient-reported outcomes for psychiatric symptoms and quality of life in Huntington's disease

INTRODUCTION

Anosognosia, defined as reduced awareness of one's deficit or symptom, is common in Huntington's disease (HD) and detectable at each disease stage. The impact of anosognosia on self-reporting in HD populations is critical to understand given growing use of patient-reported outcomes in HD clinical care and research. We aimed to determine the influence of anosognosia on patient-reported outcome measures assessing psychiatric symptoms and quality of life in HD.

METHODS

We enrolled HD patients to complete a battery of patient-reported and rater-administered measures, including the Anosognosia Scale, at baseline and 6 months later. Patient-reported outcome measures included NeuroQoL short forms for depression, anxiety, satisfaction with social roles and activities, and positive affect and well-being and Patient-Reported Outcomes Measurement Information System short forms for emotional distress-anger and sleep-related impairment. Anosognosia Scale-Difference Score indexed patient-clinician agreement on patient motor, cognitive, and behavioral abilities. We conducted multivariable linear regression analyses to quantify the association of baseline anosognosia with 6-month patient-reported outcomes.

RESULTS

Of 79 patients with complete Anosognosia Scale data at baseline, 25 (31.6 %) met the scale's criterion for anosognosia. In the regression analyses, baseline Difference Score improved prediction of 6-month patient-reported outcomes for depression, anxiety, anger, and positive affect and well-being (χ2(1) value range for likelihood ratio tests contrasting models with and without Difference Score: 13.1-20.9, p-values <0.001). Patients with more anosognosia self-reported less severe psychiatric symptoms and more positive affect and well-being.

CONCLUSION

Study results suggest that anosognosia influences patient-reported outcomes for psychiatric symptoms and quality of life in HD populations.

A multi-layered network model identifies Akt1 as a common modulator of neurodegeneration

The accumulation of misfolded and aggregated proteins is a hallmark of neurodegenerative proteinopathies. Although multiple genetic loci have been associated with specific neurodegenerative diseases (NDs), molecular mechanisms that may have a broader relevance for most or all proteinopathies remain poorly resolved. In this study, we developed a multi-layered network expansion (MLnet) model to predict protein modifiers that are common to a group of diseases and, therefore, may have broader pathophysiological relevance for that group. When applied to the four NDs Alzheimer's disease (AD), Huntington's disease, and spinocerebellar ataxia types 1 and 3, we predicted multiple members of the insulin pathway, including PDK1, Akt1, InR, and sgg (GSK-3β), as common modifiers. We validated these modifiers with the help of four Drosophila ND models. Further evaluation of Akt1 in human cell-based ND models revealed that activation of Akt1 signaling by the small molecule SC79 increased cell viability in all models. Moreover, treatment of AD model mice with SC79 enhanced their long-term memory and ameliorated dysregulated anxiety levels, which are commonly affected in AD patients. These findings validate MLnet as a valuable tool to uncover molecular pathways and proteins involved in the pathophysiology of entire disease groups and identify potential therapeutic targets that have relevance across disease boundaries. MLnet can be used for any group of diseases and is available as a web tool at http://ssbio.cau.ac.kr/software/mlnet.

Self-Awareness and therapeutic alliance in speech-language treatment of traumatic brain injury

Purpose: To investigate the relationships among client self-awareness, client perception of the therapeutic alliance, and speech-language pathologist (SLP) communicative self-awareness in dyads of SLPs and traumatic brain injury (TBI) clients.Method: Nineteen SLP-TBI client dyads (N = 38) engaged in the same collaborative therapy task. At baseline, client self-awareness and client perception of the therapeutic alliance was assessed. SLP communicative self-awareness was measured by 1) a prediction/reflection questionnaire about their own communicative behaviour, administered pre- and post-treatment sessions, and 2) self-evaluation during a novel procedure using video review within three hours after the session.Result: Client self-awareness was not associated with client perceptions of the therapeutic alliance. Client perceptions of the therapeutic alliance were related to specific communicative intentions of the SLP. Regarding SLP communicative self-awareness, SLPs predicted their primary communication modality with 66% accuracy. The video review procedure yielded more detailed SLP communicative self-awareness ratings and was completed within real-world clinical settings.Conclusion: TBI client self-awareness may not impact the establishment of a strong therapeutic alliance between SLP and client. The finding that specific communicative intentions of the SLP were related to client perception of the therapeutic alliance should prompt further efforts to measure SLP communicative intentions and behaviours during TBI treatment sessions.

A Simple and Efficient Method for the Substrate Identification of Amino Acid Decarboxylases

Amino acid decarboxylases convert amino acids into different biogenic amines which regulate diverse biological processes. Therefore, identifying the substrates of amino acid decarboxylases is critical for investigating the function of the decarboxylases, especially for the new genes predicted to be amino acid decarboxylases. In the present work, we have established a simple and efficient method to identify the substrates and enzymatic activity of amino acid decarboxylases based on LC-MS methods. We chose GAD65 and AADC as models to validate our method. GAD65 and AADC were expressed in HEK 293T cells and purified through immunoprecipitation. The purified amino acid decarboxylases were subjected to enzymatic reaction with different substrate mixtures in vitro. LC-MS analysis of the reaction mixture identified depleted or accumulated metabolites, which corresponded to candidate enzyme substrates and products, respectively. Our method successfully identified the substrates and products of known amino acid decarboxylases. In summary, our method can efficiently identify the substrates and products of amino acid decarboxylases, which will facilitate future amino acid decarboxylase studies.

Anosognosia in Dementia: Evaluation of Perfusion Correlates Using 99mTc-HMPAO SPECT and Automated Brodmann Areas Analysis

(1) Background: Considerable inconsistency exists regarding the neural substrates of anosognosia in dementia in previous neuroimaging studies. The purpose of this study was the evaluation of anosognosia perfusion correlates across various types of dementia using automated Brodmann areas (BAs) analysis and comparison with a database of normal subjects. (2) Methods: We studied 72 patients: 32 with Alzheimer’s disease, 26 with frontotemporal dementia—FTD (12 behavioral FTD, 9 semantic FTD, 5 Progressive Non-Fluent Aphasia), 11 with corticobasal syndrome, and 3 with progressive supranuclear palsy. Addenbrook’s Cognitive Examination—Revised (ACE-R) mean(±SD) was 55.6(±22.8). For anosognosia measurement, the Anosognosia Questionnaire—Dementia was used. Total anosognosia score mean(±SD) was 22.1(±17.9), cognitive anosognosia score mean(±SD) was 18.1(±15.1) and behavioral–mood anosognosia score mean(±SD) was 3.3(±4.7). (3) Results: Higher anosognosia total score was associated with hypoperfusion in the inferior temporal, anterior cingulate, and inferior frontal cortices of the right hemisphere (BAs 20R, 24R, 32R, 45R). Higher anosognosia cognitive score was correlated with hypoperfusion in the left middle and anterior temporal cortices, and right dorsal anterior cingulate cortex (BAs 21L, 22L, 32R). No association was found with behavioral–mood anosognosia. (4) Conclusions: Automated analysis of brain perfusion Single Photon Emission Computed Tomography could be useful for the investigation of anosognosia neural correlates in dementia.

Assessing Social Cognition in Older Adults: A Population-Based Study

OBJECTIVES

In a population-based study of mild cognitive impairment (MCI), to validate the assessment of social cognition in older adults.

METHODS

Cross-sectional study of 902 adults aged 65+ with mean age 76.6 years (SD 8.06). We created a social cognition composite comprising standardized z scores on the Social Norms Questionnaire and the 10-item Reading the Mind in the Eyes Test. We identified associated factors and compared sensitivity, specificity, and the area under the curve of social cognition, for MCI defined as Clinical Dementia Rating (CDR)=0.5, to those of other cognitive domains. We calculated the impact of including social cognition on the proportion neuropsychologically classified as MCI.

RESULTS

Better social cognition was associated with younger age, female sex, higher education, better general cognition (mini-mental state examination), fewer depressive symptoms, and lower CDR. Adjusting for demographics, associations with mini-mental state examination, depressive symptoms, anxiety symptoms, and subjective cognitive complaints remained significant. The sensitivity and specificity of social cognition for CDR=0.5 were comparable to those of the traditional 5 cognitive domains. Including social cognition as a sixth domain of cognition resulted in a 5% increase in the proportion classified as MCI.

CONCLUSIONS

Brief objective assessment of social cognition may enhance cognitive assessment of older adults.

The Impact of Anosognosia on Clinical and Patient-Reported Assessments of Psychiatric Symptoms in Huntington's Disease

BACKGROUND

Psychiatric symptoms are widely prevalent in Huntington's disease (HD) and exert greater impact on quality of life than motor manifestations. Despite this, psychiatric symptoms are frequently underrecognized and undertreated. Lack of awareness, or anosognosia, has been observed at all stages of HD and may contribute to diminished patient self-reporting of psychiatric symptoms.

OBJECTIVE

We sought to evaluate the impact of anosognosia on performance of commonly used clinical rating scales for psychiatric manifestations of HD.

METHODS

We recruited 50 HD patients to undergo a formal psychiatrist evaluation, the Problem Behavior Assessment-Short Form (PBA-s), and validated self-report rating scales for depression, anxiety, and anger. Motor impairment, cognitive function, and total functional capacity were assessed as part of clinical exam. Patient awareness of motor, cognitive, emotional, and functional capacities was quantified using the Anosognosia Rating Scale. Convergent validity, discriminant validity, classification accuracy, and anosognosia effect was determined for each psychiatric symptom rating scale.

RESULTS

Anosognosia was identified in one-third of patients, and these patients underrated the severity of depression and anxiety when completing self-report instruments. Anosognosia did not clearly influence self-reported anger, but this result may have been confounded by the sub-optimal discriminant validity of anger rating scales.

CONCLUSION

Anosognosia undermines reliability of self-reported depression and anxiety in HD. Self-report rating scales for depression and anxiety may have a role in screening, but results must be corroborated by provider and caregiver input when anosognosia is present. HD clinical trials utilizing patient-reported outcomes as study endpoints should routinely evaluate participants for anosognosia.

Sleep Dysfunction in Huntington’s Disease: Perspectives from Patients

Background: Despite the abundance of clinical tools, sleep disorders are still not routinely evaluated in patients with Huntington’s disease (HD). Sleep disturbances can exacerbate cognitive impairment and mood disorders and seriously affect the life of the patients and their families. Objective: The current study was designed to investigate sleep quality and its association with clinical symptoms in HD. As an exploratory aim, we also evaluated sleep quality in caregivers of patients with HD. Methods: Twenty-nine patients with HD and 22 caregivers completed a series of self-reported questionnaires about sleep quality and pattern, cognitive function, and depression and anxiety symptoms. Spearman correlation analyses were performed to ascertain the association between sleep quality and severity of self-perceived clinical symptoms. Results: The primary sleep complaints reported by the patients were related to waking up in the middle of the night or early in the morning; and increased sleep latency. Seventeen of 29 HD patients (59%) and 12 of 22 caregivers (55%) were classified as “poor” sleepers. Worse sleep quality among HD patients was associated with greater severity of anxiety and depression symptoms. Importantly, a decline in sleep quality was associated with decreased self-perceived cognitive function for both HD patients and caregivers. Conclusion: Increasing awareness and improving our understanding of sleep dysfunction in HD is imperative for individuals with HD and indirectly, their caregivers. Regularly incorporating sleep assessments when evaluating HD patients should be considered to address this troublesome nonmotor symptom.

Evaluation of a performance-rating method to assess awareness of cognitive functioning in Huntington's disease

Objective: Anosognosia, or lack of awareness of symptoms, is commonly observed in Huntington's disease (HD) using patient/informant-report discrepancy methods. The purpose of this study was to examine the utility of a performance-rating method for assessing awareness of cognitive performance in HD.Method: Persons with manifest HD (n = 54) rated their performance on the daily living tests from the Neuropsychological Assessment Battery (NAB) using a bell curve. We also examined patient/informant-report discrepancies of executive functioning (FrSBe) in a subset (n = 47) of patients and their informants.Results: Patients were able to reliably use our method of categorizing their performance as evidenced by significant correlations between verbal descriptions of their performance and the percentile ratings they indicated on the bell curve. Patients across the range of observed Unified HD Rating Scale motor scale scores rated their performance on the NAB tasks significantly higher than actual performance for both pretest prediction and posttest evaluation ratings. Only patients with more severe motor impairment underestimated their problems relative to informant report on the FrSBe.Conclusions: This is the first study to use a performance-rating method for examining awareness in HD. Patients could reliably use this performance-based bell curve method to provide accurate estimations of their performance and as a group they tended to overestimate performance as has been demonstrated in previous studies. Unlike previous studies using self-report methodology, we also demonstrated decreased awareness in the persons with HD with less severe motor impairment using the performance-rating method, suggesting the two methods may measure different constructs of awareness.

The Neuropsychology of Huntington's Disease

Huntington's disease is an inherited, degenerative brain disease, characterized by involuntary movements, cognitive disorder and neuropsychiatric change. Men and women are affected equally. Symptoms emerge at around 40 years, although there is wide variation. A rare juvenile form has onset in childhood or adolescence. The evolution of disease is insidious and structural and functional brain changes may be present more than a decade before symptoms and signs become manifest. The earliest site of pathology is the striatum and neuroimaging measures of striatal change correlate with neurological and cognitive markers of disease. Chorea and other aspects of the movement disorder are the most visible aspect of the disease. However, non-motor features have greatest affect on functional independence and quality of life, so require recognition and management. The evidence-base for non-pharmacological treatments in Huntington's disease is currently limited, but recent intervention studies are encouraging.

The many facets of unawareness in huntington disease

Background

Unawareness or diminished awareness is present when a patient's perception of obvious disease manifestations and impact differ from that of observers such as clinicians or family members.

Methods

We examined studies that specifically investigate unawareness in Huntington disease (HD).

Results

Unawareness of motor, cognitive, behavioral, and functional aspects of HD has been documented throughout the disease course. This can occur at motor and cognitive onset but is more pronounced as the disease progresses.

Discussion

We discuss the implications for diagnosis, symptom report at presentation, timing of diagnosis, acceptance of symptomatic care strategies, and reporting in clinical trials. Assessments of work place competency, discrimination, driving, and the particular challenges of isolated patients without caregivers are described. Engaging with a person who is unaware of their disease or its impact presents a number of conflicts, including maintaining the right to autonomy, privacy, confidentiality, and independence while recognizing concerns for the wellbeing of the vulnerable person with HD and their caregiver when the unaware person refuses assistance. Unawareness is seen increasingly as neurologically based due to the impairment of functional networks, predominantly in nondominant frontostriatal pathways.

Huntington Disease - principles and practice of nutritional management

Huntington disease (HD) is a degenerative brain disease clinically manifested by the characteristic triad: physical symptoms including involuntary movements and poor coordination, cognitive changes with less ability to organize routine tasks, and some emotional and behavioral disturbances. For patients with HD, feeding is one of the problems they have to face. People with HD often have lower than average body weight and struggle with malnutrition. As a part of therapy, good nutrition is an intervention maintaining health and functional ability for maximally prolonged time. In the early stages of HD, small amounts of blenderized foods given orally are recommended. In more advanced stages, enteral nutrition is essential using gastric, or jejunal tubes for short term. Most severe cases require gastrostomy or gastrojejunostomy. Although enteral feeding is well tolerated by most of the patients, a number of complications may occur, including damage to the nose, pharynx, or esophagus, aspiration pneumonia, sinusitis, metabolic imbalances due to improper nutrient and fluid supply, adverse effects affecting gastrointestinal system, and refeeding syndrome.

Non-Alzheimer's disease-related memory impairment and dementia

Although Alzheimer's disease (AD) is a common cause of memory impairment and dementia in the elderly disturbed memory function is a widespread subjective and/or objective symptom in a variety of medical conditions. The early detection and correct distinction of AD from non-AD memory impairment is critically important to detect possibly treatable and reversible underlying causes. In the context of clinical research, it is crucial to correctly distinguish between AD or non-AD memory impairment in order to build homogenous study populations for the assessment of new therapeutic possibilities. The distinction of AD from non-AD memory impairment may be difficult, especially in mildly affected patients, due to an overlap of clinical symptoms and biomarker alterations between AD and certain non-AD conditions. This review aims to describe recent aspects of the differential diagnosis of AD and non-AD related memory impairment and how these may be considered in the presence of memory deficits.

Identifying Motor, Emotional-Behavioral, and Cognitive Deficits that Comprise the Triad of HD Symptoms from Patient, Caregiver, and Provider Perspectives

BACKGROUND

The objective of this study was to identify important attributes associated with the triad of symptoms (cognition, emotional-behavioral, and motor) of Huntington's disease (HD) from patient, caregiver, and medical provider perspectives to facilitate development of a new disease-specific, health-related quality of life (HRQOL) instrument.

METHODS

We conducted a targeted literature review of HD and HRQOL instruments, expert surveys, and patient and caregiver phone-based interviews to extract information on the symptoms and issues most relevant to the HD symptom triad (HD triad). The data collected from these sources were used to generate themes and subdomains and to develop an integrated schema that highlights the key dimensions of the triad.

RESULTS

THE SEARCH IDENTIFIED THE FOLLOWING AREAS: emotional functioning/behavioral changes (e.g., positive emotions, sadness/depression); cognitive functioning (e.g., memory/learning, attention/comprehension); physical functioning (e.g., motor functioning, medication); social functioning (e.g., leisure, interpersonal relationships); end-of-life concerns/planning; and gene testing. Fifteen individuals diagnosed with HD and 16 HD caregivers, recruited from several Huntington's Disease Society of America support group networks, completed phone interviews. Nineteen US medical providers who specialize in HD completed the online survey. Twenty-six subdomains of the HD symptom triad (seven cognition, 12 emotional-behavioral, and seven motor) emerged relatively consistently across patient, caregiver, and provider samples. These included movements/chorea, memory impairment, depression, and anxiety.

DISCUSSION

Based on an integrated, mixed-methods approach, important HD triad symptom were identified and organized into a guiding schema. These patient-, caregiver-, and provider-triangulated data served as the basis for development of a HD-specific HRQOL instrument, the HD-PRO-TRIAD™.

"Forgetting to remember" in Huntington's disease: a study of laboratory, semi-naturalistic, and self-perceptions of prospective memory

Prospective memory (PM) is dependent on executive processes known to be impaired in Huntington's disease (HD); however, no study to the authors' knowledge has investigated PM in this group. We examined performance-based, semi-naturalistic, and self-reported PM in 20 individuals diagnosed with mild-moderate HD and 20 demographically similar controls. Relative to controls, HD participants demonstrated significantly lower scores in time-based PM, event-based PM (at a trend level), and the semi-naturalistic PM trial, all of which were marked by omission errors. HD participants demonstrated comparable recognition memory for the PM intentions relative to controls. HD and control participants also showed comparable scores in self-reported PM complaints. The results suggest that HD is associated with deficits in the strategic aspects of PM. HD-associated PM deficits also are evident in real-world situations, which may relate to an apparent meta-memory deficit for PM functioning as indicated by HD participants' overestimation of their PM performance on self-report.