Christian Chicherio

• Dr psych.
• Medical Professional at Hôpitaux Universitaires de Genève

Harmonized neuropsychological assessment for neurocognitive disorders (NCDs) is an urgent priority in clinics. Neuropsychology assessments in NCDs seldom include tests exploring social cognitive skills. In 2022, we launched the SIGNATURE initiative to optimize socio-cognitive assessment in NCDs. Here, we report findings from the first initiative ph...

INTRODUCTION Resilience, the ability to maintain cognition or brain integrity despite Alzheimer's disease (AD) pathology, is often quantified using the residual approach. However, the variability in methodology and correction methods for this approach raises concerns about the interpretability of findings across studies. METHODS We assessed brain...

Background The Three‐Objects‐Three‐Places (3O3P) test is a 5‐min screen for episodic memory impairment due to Alzheimer's disease, known for its briefness and easy administration, culture‐ and language‐free nature, and the absence of specific equipment. However, no studies have validated its potential in memory clinic cohorts. The aim of this study...

Background Resilience, the ability to maintain normal cognition (cognitive resilience, CR) or brain integrity (brain resilience, BR) despite neuropathological burden, is often quantified using the residual approach. This method calculates residuals from a linear regression where the dependent variable is brain volume or cognition, and the independe...

Background Metacognition may give useful insight in early stages of Alzheimer’s disease (AD) continuum. Recent studies suggest differences in the ability of judging their own cognitive performance along clinical stages. For instance, subjects with mild cognitive impairment (MCI) overestimate, whereas people with subjective cognitive decline (SCD) t...

Background: Harmonising assessment for neurocognitive disorders (NCDs) is an urgent priority for both clinical settings and research. In 2022, we launched the SIGNATURE initiative with the aim to harmonize and optimise the use of socio-cognitive assessments in NCDs. Hereby, we report findings from the first phase of the initiative including the eva...

Cognitive complaints are common in elderly subjects and are a frequent reason for referral to memory clinics. If the complaints are not associated with objective cognitive impairment, the condition is labelled subjective cognitive decline (SCD). SCD is often considered as a stage antedating objective impairment, and an at‐risk condition for subsequ...

Introduction: Subjective Cognitive Decline (SCD) is characterized by subjective cognitive concerns without objective cognitive impairment and is considered a risk factor for cognitive decline and dementia. However, most SCD patients will not develop neurodegenerative disorders, yet they may suffer from minor psychiatric, neurological, or somatic c...

Background The Three‐Objects‐Three‐Places (3O3P) test has been developed as a quick screen for episodic memory impairment due to Alzheimer’s Disease (AD). The examiner shows the patient three objects and hides them in three separate places. The patient is later asked what the objects and hiding places were, and which object was hidden where, produc...

Background Subjective cognitive decline (SCD) is the self‐reported experience of decrease in cognitive function in absence of cognitive impairment. This condition is common in elderly subjects and is a frequent reason for referral to memory clinics. SCD is often considered as a stage antedating objective impairment, and an at‐risk condition for sub...

Background: Harmonisation of evidence-based neuropsychological protocols among different countries represents a priority for the benefit of researchers, clinicians and most importantly patients. Currently, no consensus on a uniform operationalization of socio-cognitive measures for neurocognitive disorders (NCDs) in memory clinics exists. The inter...

Purpose The ATN model represents a research framework used to classify subjects based on the presence or absence of Alzheimer’s disease (AD) pathology through biomarkers for amyloid (A), tau (T), and neurodegeneration (N). The aim of this study was to assess the relationship between ATN profiles defined through imaging and cognitive decline in a me...

Background: Subjective Cognitive Decline (SCD) is characterized by subjective cognitive complaints without objective cognitive impairment and is considered a risk factor for cognitive decline and dementia. However, most SCD patients will not develop neurodegenerative disorders, yet they may suffer from minor psychiatric, neurological, or somatic co...

The Three‐Objects‐Three‐Places Psychological Test (3O3P) assesses episodic memory and has been developed to screen for Alzheimer’s Disease (AD). To perform the test, the clinician shows the patient three objects and hides them in three separate locations. The patient is later asked what the objects and hiding places were, and which object was hidde...

Brain resistance (R) has been defined as the capacity of the brain to preserve its integrity and to sustain normal cognition despite aging. Resilience has been defined as the capacity to sustain a better‐than‐expected brain integrity (brain resilience,BR) or cognitive performance (cognitive resilience,CR) in presence of pathological burden. There i...

Introduction: Harmonized neuropsychological assessment for neurocognitive disorders, an international priority for valid and reliable diagnostic procedures, has been achieved only in specific countries or research contexts. Methods: To harmonize the assessment of mild cognitive impairment in Europe, a workshop (Geneva, May 2018) convened stakeho...

Purpose Assess the individual and combined diagnostic value of amyloid-PET and tau-PET in a memory clinic population. Methods Clinical reports of 136 patients were randomly assigned to two diagnostic pathways: AMY-TAU, amyloid-PET is presented before tau-PET; and TAU-AMY, tau-PET is presented before amyloid-PET. Two neurologists independently asse...

Background Subjective cognitive decline (SCD) is the subjective perception of a decline in memory and/or other cognitive functions in the absence of objective evidence. Some SCD individuals however may suffer from very early stages of neurodegenerative diseases (such as Alzheimer’s disease, AD), minor psychiatric conditions, neurological, and/or so...

BACKGROUND. Subjective cognitive decline (SCD) is the subjective perception of a decline in memory and/or other cognitive functions in the absence of objective evidence. Some SCD individuals however may suffer from very early stages of neurodegenerative diseases (such as Alzheimer’s disease, AD), minor psychiatric conditions, neurological, and/or s...

Executive functions, which are high-level effortful cognitive functions that facilitate the achievement of an intentional goal, generally decline with age. The capacity to inhibit an action, an urge, a thought, or an emotion, intentionally is an executive function that plays a crucial role in daily life. The aging process, which affects this inhibi...

Background Advances in the Alzheimer’s disease (AD) field have enhanced awareness on brain health and prevention. This brings an increasing number of adults to ask for help in memory clinics for mild forgetfulness, leading to the increased use of health care resources. Nowadays, about 25% of memory clinics patients complain of cognitive decline in...

Purpose The A/T/N model is a research framework proposed to investigate Alzheimer’s disease (AD) pathological bases (i.e., amyloidosis A, neurofibrillary tangles T, and neurodegeneration N). The application of this system on clinical populations is still limited. The aim of the study is to evaluate the topography of T distribution by 18F-flortaucip...

Background: The exact relationship between delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (aSAH) and neuropsychological impairment remains unknown, as previous studies lacked a baseline examination after aneurysm occlusion but before the DCI-period. Neuropsychological evaluation of acutely ill patients is often applie...

Background: In the elderly, physical activity (PA) enhances cognitive performances, increases brain plasticity and improves brain health. The neurotrophic hypothesis is that the release of brain-derived neurotrophic factor (BDNF), which is implicated in brain plasticity and cognition, is triggered by PA because motoneurons secrete BDNF into the blo...

It is well-known that processing speed and executive functions decline with advancing age. However, physical activity (PA) has a positive impact on cognitive performances in aging, specifically for inhibition. Less is known concerning intraindividual variability (iiV) in reaction times. This study aims to investigate the influence of PA and sex dif...

The present study is the first so far in empirically testing the recent conceptual view that the number of chronic diseases may mediate between the build-up of cognitive reserve (e.g., by educational attainment and cognitive level of job) on the one hand and cognitive performance on the other. We assessed Psychometric tests on processing speed and...

We investigated whether the relation of educational attainment and cognitive level of job to performance in verbal ability and processing speed in old age was mediated via the number of chronic diseases. A total of 2,812 older adults participated. Psychometric tests on verbal ability and processing speed were administered. Individuals were intervie...

L’essentiel pour la pratique • Les déficits neuropsychologiques à la suite d’une hémorragie sousarachnoïdienne (HSA) anévrismale ont une prévalence élevée et ne sont pas encore caractérisés de manière adéquate et systématique. • Même pour les patients bénéficiant d’une bonne évolution clinique, il persiste des déficits qui entravent le retour à un...

Das Wichtigste für die Praxis • Neuropsychologische Defizite nach aneurysmatischer Subarachnoidalblutung (aSAB) haben eine hohe Prävalenz und werden bisher nur unzureichend und unsystematisch abgeklärt. • Selbst bei Patienten mit gutem klinisch-funktionellem Ergebnis nach aSAB ver- oder behindern diese Störungen häufig die Rückkehr zur prämorbiden...

In a high proportion of patients with favorable outcome after aneurysmal subarachnoid hemorrhage (aSAH), neuropsychological deficits, depression, anxiety, and fatigue are responsible for the inability to return to their regular premorbid life and pursue their professional careers. These problems often remain unrecognized, as no recommendations conc...

Objective: The cause precipitating intracranial aneurysm rupture remains unknown in many cases. It has been observed that aneurysm ruptures are clustered in time but the trigger mechanism remains obscure. As solar activity has been associated with cardiovascular mortality and morbidity we decided to study its association to aneurysm rupture in the...

Higher cognitive functions, such as human perceptual decision making, require information processing and transmission across wide-spread cortical networks. Temporally synchronized neural firing patterns are advantageous for efficiently representing and transmitting information within and between assemblies. Computational, empirical, and conceptual...

To date, cognitive intervention research has provided mixed but nevertheless promising evidence with respect to the effects of cognitive training on untrained tasks (transfer). However, the mechanisms behind learning, training effects and their predictors are not fully understood. Moreover, individual differences, which may constitute an important...

Some eighty years after the discovery of the human electroencephalogram (EEG) and its dominant rhythm, alpha (~ 10 Hz), the neurophysiological functions and behavioral correlates of alpha oscillations are still under debate. Similarly, the biological mechanisms contributing to the general factor of intelligence, or g, have been under scrutiny for d...

The individual alpha frequency (IAF) of the human EEG reflects systemic properties of the brain, is highly heritable, and relates to cognitive functioning. Not much is known about the modifiability of IAF by cognitive interventions. We report analyses of resting EEG from a large-scale training study in which healthy younger (20-31 years, N = 30) an...

La variabilità intraindividuale (VII) è divenuta un oggetto di studio di varie ricerche interessate a comprendere i meccanismi che spiegano il Disturbo da Deficit di Attenzione/Iperattività – ADHD. Individui con ADHD mostrano in modo sistematico tempi di risposta (TR) più lenti e variabili rispetto a individui con sviluppo normale in varie prove co...

The present study investigates intraindividual variability (IIV) in the Color-Stroop test and in a simple reaction time (SRT) task. Performance level and variability in reaction times (RTs)-quantified with different measures such as individual standard deviation (ISD) and coefficient of variation (ICV), as well as ex-Gaussian parameters (mu, sigma,...

L’invecchiamento cognitivo si caratterizza per una ampia variabilità interindividuale non solo a livello della prestazione comportamentale ma anche, rispetto ai cambiamenti, dipendenti dall’età, a livello chimico, strutturale e funzionale del cervello. Tra le ipotesi oggi avanzate per spiegare le differenze individuali nel mantenimento di un compor...

Cognitive aging is characterized by large interindividual variability at the level of behavioral performance and with respect to age-related modifications in the brain structure, function, and chemistry. The concept of reserve capacity has been proposed to account for differences between individuals in the ability to preserve a functionally and app...

It has been suggested that intraindividual variability (IIV) in neuropsychological tasks may be a specific characteristic of Attention-Deficit Hyperactivity Disorder (ADHD), but previous research has not thoroughly examined whether IIV also concerns academic performance or other types of developmental disabilities. The present study investigates th...

The brain-derived neurotrophic factor (BDNF) plays an important role in activity-dependent synaptic plasticity, which underlies learning and memory. In a sample of 948 younger and older adults, we investigated whether a common Val66Met missense polymorphism (rs6265) in the BDNF gene affects the serial position curve—a fundamental phenomenon of asso...

Individual differences in cognitive performance increase from early to late adulthood, likely reflecting influences of a multitude of factors. We hypothesize that losses in neurochemical and anatomical brain resources in normal aging modulate the effects of common genetic variations on cognitive functioning. Our hypothesis is based on the assumptio...

In the past, research on lifespan changes in intelligence hits regarded variability primarily as an outcome of development. Here, we argue that it may also function as an agent of ontogeneticchanges in cognitive functioning. We first review the conceptual and methodological status of variability in psychometric, experimental, and neuroscience appro...

The present article describes the development, administration, scoring procedure and sampling of a Reading Span Task assessing the controlled attention component of working memory. This task was standardized on a French speaking population of 775 young and older adults. The task holds satisfactory reliability, validity and sensibility and thus appe...

Functional activation protocols are widely applied for the study of brain-cognition relations. Only few take advantage of the intrinsic characteristics of SPECT, particularly those allowing cognitive assessment outside of the camera, in settings close to the standard clinical or laboratory ones. The purpose of the study was to assess the feasibilit...

We demonstrate that common genetic polymorphisms contribute to the increasing heterogeneity of cognitive functioning in old age. We assess two common Val/Met polymorphisms, one affecting the Catechol-O-Methyltransferase (COMT) enzyme, which degrades dopamine (DA) in prefrontal cortex (PFC), and the other influencing the brain-derived neurotrophic f...

Le développement récent des techniques d’imagerie cérébrale a permis d’ouvrir de nouvelles perspectives quant à l’étude des changements avec l’âge dans les bases neuro-fonctionnelles des comportements. S’il est indéniable que chez l’adulte, l’avancée en âge est associée à des pertes neuro-structurelles, les données actuelles suggèrent que le cervea...

The development of brain imaging techniques has opened new perspectives for the study of age-related changes in the neurofunctional bases of behavior. While advancing age is indisputably associated with neuro-structural losses, recent data nonetheless suggest that the aging brain is capable of functional reorganizations. More, some these age-relate...

The development of brain imaging techniques has opened new perspectives for the study of age-related changes in the neurofunctional bases of behavior. While advancing age is indisputably associated with neuro-structural losses, recent data nonetheless suggest that the aging brain is capable of functional reorganizations. More, some these age-relate...

To explore relationships between scuba diving activity, brain, and behaviour, and more specifically between global cerebral blood flow (CBF) or cognitive performance and total, annual, or last 6 months' frequencies, for standard dives or dives performed below 40 m, in cold water or warm sea geographical environments. A prospective cohort study was...

The goal of this study was to explore in patients with Alzheimer's disease (AD) the brain correlates of free and cued recall performance using an adaptation of the procedure developed by Grober and Buschke (1987). This procedure, which ensures semantic processing and coordinates encoding and retrieval, has been shown to be very sensitive to an earl...

The central hypothesis of the study which has been carried out as part of the NRP38 program, is that perturbations of brain energy metabolism are critically involved in the neurodegeneration occurring in Alzheimer's disease (AD) and that they may correlate with early cognitive dysfunctioning. In the present multidisciplinary study we set out to mon...

Hysterical conversion disorders refer to functional neurological deficits such as paralysis, anaesthesia or blindness not caused by organic damage but associated with emotional "psychogenic" disturbances. Symptoms are not intentionally feigned by the patients whose handicap often outweighs possible short-term gains. Neural concomitants of their alt...

Dementia is becoming a major health problem as the population of the Northern Hemisphere ages. Early differential diagnosis between normal cognitive decline and dementia is particularly difficult. If psychometric evaluation can contribute to the diagnosis, quantitative cerebral functional imaging would play an important role. We therefore proposed,...

Functional imaging methods allow to study cerebral activity in healthy and pathologic populations, both from a clinical and a experimental viewpoint. For example, positron emission tomography (PET) was used to emphasize brain regions involved in memory functioning of control population, and also to help in the diagnosis of Alzheimer's disease. PET...

Most previous PET studies investigating the central executive (CE) component of working memory found activation in the prefrontal cortex. However, the tasks used did not always permit to distinguish precisely the functions of the CE from the storage function of the slave systems. The aim of the present study was to isolate brain areas that subserve...