Stratified medicine has been successfully used in many areas of medicine, perhaps most notably oncology. There is now both a growing evidence base and mounting enthusiasm, supported at a governmental level and across industry, academia and clinical medicine, to apply this approach to neurodegenerative illnesses, including dementia, as these provide the greatest clinical and social challenge of our times. In this article we consider definitions of stratified medicine, look at its application in other medical specialties, review the national context in the UK and consider the current state, future potential and specific considerations of applying stratified medicine to dementia.

Studies show that vitamin D (vit-D) (25(OH)D), the bioactive metabolite (1,25(OH)2D3) and vit-D receptors (vit-D receptor; protein disulphide isomerase, family A member 3) are expressed throughout the brain, particularly in regions pivotal to learning and memory. This has led to the paradigm that avoiding vit-D deficiency is important to preserve cognitive function. However, presently, it is not clear if the common clinical measure of serum 25(OH)D serves as a robust surrogate marker for central nervous system (CNS) homeostasis or function. Indeed, recent studies report CNS biosynthesis of endogenous 25(OH)D, the CNS expression of the CYP group of enzymes which catalyse conversion to 1,25(OH)2D3 and thereafter, deactivation. Moreover, in the periphery, there is significant ethnic/genetic heterogeneity in vit-D conversion to 1,25(OH)2D3 and there is a paucity of studies which have actually investigated vit-D kinetics across the cerebrovasculature. Compared with peripheral organs, the CNS also has differential expression of receptors that trigger cellular response to 1,25(OH)2D3 metabolites. To holistically consider the putative association of peripheral (blood) abundance of 25(OH)D on cognitive function, herein, we have reviewed population and genetic studies, pre-clinical and clinical intervention studies and moreover have considered potential confounders of vit-D analysis.

Exactly 200 years ago, the London surgeon-apothecary James Parkinson (1755-1824) published a 66-page-long booklet entitled An Essay on the Shaking Palsy, which contains the first clear clinical description of the shaking palsy or paralysis agitans, which we now refer to as Parkinson’s disease. However, the value of this essay was not fully recognized during Parkinson’s lifetime, which spanned the American Revolution, the French Revolution, and the Napoleonic Wars. James Parkinson was one of the most singular figures of his time and place. He was successively or concomitantly a virulent political activist, a popular medical writer, a scholarly medical contributor, a highly appreciated parish doctor, a prominent amateur chemist, a devoted madhouse doctor, and a renowned paleontologist. It is that branch of geology that brought Parkinson fame during his lifetime. He was an insatiable collector of fossils, minerals, and shells that came to form the core of the museum that he set out at his home in Shoreditch, England. These specimens are beautifully illustrated in his Organic Remains of a Former World (1804-1811), a three-volume treatise that rapidly became a standard paleontology textbook. Parkinson was a founding member of the Geological Society of London, and in recognition of his contribution to the nascent field of paleontology his name was given to many fossils, particularly ammonites (e.g. Nautilus parkinsoni). Hence, we owe much to Mr. Parkinson, the Paleontologist, as he used to be referred to after his death, for such a vast and multifaceted contribution to natural science and medicine.

Purpose: To undertake a randomised controlled trial to test the benefits of cognitive training (CT) vs. cognitive stimulation (CS) on general cognitive function and memory in mild Alzheimer's disease (mAD).

Method: A consecutive series of 55 mAD outpatients was randomly allocated to one of the three conditions, namely two experimental interventions (CT and CS; 17 participants each) and a control dementia (no intervention) group (CD; 21 participants). Participants in the experimental conditions received a 4-month individual intervention programme.

Results: The participants in the CT condition demonstrated a large improvement in general cognitive state with moderate gains in areas of memory targeted by the intervention (semantic memory, naming and retrieval ability) 12 months after baseline measurement compared to the other two conditions. In addition, CT seemed to generalise the other cognitive abilities that were not directly targeted with small gains noted in other domains of cognition (prospective memory, face recognition, name a person) compared to CS and CD. Participants in both the CS and CD conditions showed significant general cognitive decline, even though CS was found to ameliorate the trajectory of this decline.

Objective: Prospective memory (PM) is a cognitive function defined as the ability to perform an intention at an appropriate moment in the future. In the aging population, PM is essential for maintaining independent daily living. Introduced as a simple and quick way to assess PM in clinical settings, the envelope task has to date received very limited empirical and practical interest. Methods: The present study investigated the task’s clinical utility in detecting PM impairment in a sample composed of 49 healthy older adults (OA), 41 patients with Alzheimer’s disease, and 64 individuals with amnestic and nonamnestic mild cognitive impairment (MCI) of heterogeneous etiology: 17 of idiopathic nature, 20 presenting an idiopathic rapid-eye movement sleep behaviour disorder, and 27 patients diagnosed with idiopathic Parkinson’s disease. Results: The envelope task was highly sensitive and specific in discriminating Alzheimer’s disease patients from OA. Although it was specific in distinguishing MCI individuals from OA, its sensitivity was modest, especially in patients presenting a nonamnestic MCI subtype. Conclusions: Given its high specificity and simple low-cost administration procedure, the envelope task is a promising instrument for clinicians who seek to rapidly assess PM impairment in their daily practice.

Objective: Patients with Parkinson’s disease (PD) can show impaired self-awareness of motor deficits (ISAm). We developed a new scale that measures ISAm severity of hyper- and hypokinetic movements in PD during medication on state and defined its psychometric criteria. Method: Included were 104 right-handed, non-depressed, non-demented patients. Concerning ISAm, 38 motor symptoms were assessed using seven tasks, which were performed and self-rated concerning presence of deficit (yes/no) by all patients. The whole procedure was videotaped. Motor symptoms were then evaluated by two independent experts, blinded for patient’s ratings, concerning presence, awareness of deficit, and severity. Exploratory principal component analysis (promax rotation) was applied to reduce items. Principal axis factoring was conducted to extract factors. Reliability was examined regarding internal consistency, split-half reliability, and interrater reliability. Validity was verified by applying two additional measures of ISAm. Results: Of the initial 38 symptoms, 15 remained, assessed in five motor tasks and merged to a total severity score. Factor analysis resulted in a four factor solution (dyskinesia, resting tremor right hand, resting tremor left hand, bradykinesia). For all subscales and the total score, measures of reliability (values 0.64–0.89) and validity (effect sizes>0.3) were satisfactory. Descriptive results showed that 66% of patients had signs of ISAm (median 2, range 0–15), with ISAm being most distinct for dyskinesia. Conclusions: We provide the first validation of a test for ISAm in PD. Using this instrument, future studies can further analyze the pathophysiology of ISAm, the psychosocial sequelae, therapeutic strategies and compliance with therapy. (JINS, 2015, 21, 1–10)

Facial expression recognition impairment has been reported in Parkinson’s disease. While some authors have referred to specific emotional disabilities, others view them as secondary to executive deficits frequently described in the disease, such as working memory. The present study aims to analyze the relationship between working memory and facial expression recognition abilities in Parkinson’s disease. We observed 50 patients with Parkinson’s disease and 49 healthy controls by means of an n-back procedure with four types of stimuli: emotional facial expressions, gender, spatial locations, and non-sense syllables. Other executive and visuospatial neuropsychological tests were also administered. Results showed that Parkinson’s disease patients with high levels of disability performed worse than healthy individuals on the emotional facial expression and spatial location tasks. Moreover, spatial location task performance was correlated with executive neuropsychological scores, but emotional facial expression was not. Thus, working memory seems to be altered in Parkinson’s disease, particularly in tasks that involve the appreciation of spatial relationships in stimuli. Additionally, non-executive, facial emotional recognition difficulty seems to be present and related to disease progression. (JINS, 2014, 20, 1–10)

Executive functions refer to a constellation of higher-level cognitive abilities that enable goal-oriented behavior. The NIH EXAMINER battery was designed to assess executive functions comprehensively and efficiently. Performance can be summarized by a single score, the “Executive Composite,” which combines measures of inhibition, set-shifting, fluency, and working memory. We evaluated the ecological validity of the Executive Composite in a sample of 225 mixed neurological patients and controls using the Frontal Systems Behavior Scale (FrSBe), an informant-based measure of real-world executive behavior. In addition, we investigated the neuroanatomical correlates of the Executive Composite using voxel-based morphometry in a sample of 37 participants diagnosed with dementia, mild cognitive impairment, or as neurologically healthy. The Executive Composite accounted for 28% of the variance in Frontal Systems Behavior Scale scores beyond age. Even after including two widely used executive function tests (Trails B and Stroop) as covariates, the Executive Composite remained a significant predictor of real-world behavior. Anatomically, poorer scores on the Executive Composite were associated with smaller right and left dorsolateral prefrontal volumes, brain regions critical for good executive control. Taken together, these results suggest that the Executive Composite measures important aspects of executive function not captured by standard measures and reflects the integrity of frontal systems. (JINS, 2013, 19, 1–9)

Background: Knowledge about sleep complaints of caregivers of patients with Alzheimer's disease (AD) and Parkinson's disease (PD) is limited, and we lack information about the relationship between caregivers’ sleep problems and their quality of life (QoL).

Methods: We evaluated subjective sleep quality and its relationship to QoL in a group of 80 caregivers of patients with AD (ADCG, n = 40) and PD (PDCG, n = 40), and in 150 controls. Information about night-time complaints was collected using the Pittsburgh Sleep Quality Index (PSQI). QoL was measured using the McGill QoL Questionnaire.

Results: Eighteen ADCG (45%), 22 PDCG (55%), and 45 (30%) controls reported poor sleep quality. Mean global PSQI score of PDCG (6.25 ± 3.9) was not significantly different from that of ADCG (5.8 ± 3.5; p = 0.67). However, both PDCG and ADCG scored significantly higher than control group (4.3 ± 3.1; p < 0.01). ADCG frequently reported difficulties falling asleep (72.5%) and disturbed sleep (100%). PDCG reported reduced subjective sleep quality (80%) and increased sleep disturbances (100%). Poor sleep quality was associated with depressive symptoms and correlated with QoL in caregivers of both groups, particularly the psychological symptoms domain.

Conclusions: Among caregivers of patients with AD and PD, poor sleep quality is frequent and significantly linked to QoL and depressive symptoms. Identifying the nature of sleep disturbances not only in patients but also in their caregivers is important as appropriate treatment may lead to a better management of the needs of families coping with these patients.

Religion is central to the lives of billions of people worldwide. To probe processing dynamics of religious cognition and its potential brain correlates, we used a novel priming procedure to assess the integrity of religious and control semantic networks in patients with Parkinson’s disease (PD) and controls. Priming for control, but not religious, concepts was intact in PD patients. Patients with left-onset (right-forebrain disease) evidenced severe impairment activating religious concepts. We next modeled the priming performance with modified cable equations. These analyses suggested that deficient performance of PD patients on activation of religious concepts was due to a change in the time constants governing gain and rate of decay of activation in these semantic networks. These modeling results are consistent with dopaminergic dysfunction in right-sided striatal-prefrontal networks. We conclude that right striatal-prefrontal dopaminergic networks support activation of complex religious concepts but not equally complex and related control concepts. (JINS, 2010, 16, 252–261.)