Artificial intelligence (AI) for neurologists: do digital neurones dream of electric sheep?

Artificial intelligence (AI) is routinely mentioned in journals and newspapers, and non-technical outsiders may have difficulty in distinguishing hyperbole from reality. We present a practical guide to help non-technical neurologists to understand healthcare AI. AI is being used to support clinical decisions in treating neurological disorders. We introduce basic concepts of AI, such as machine learning and natural language processing, and explain how AI is being used in healthcare, giving examples its benefits and challenges. We also cover how AI performance is measured, and its regulatory aspects in healthcare. An important theme is that AI is a general-purpose technology like medical statistics, with broad utility applicable in various scenarios, such that niche approaches are outpaced by approaches that are broadly applicable in many disease areas and specialties. By understanding AI basics and its potential applications, neurologists can make informed decisions when evaluating AI used in their clinical practice. This article was written by four humans, with generative AI helping with formatting and image generation.

Diagnostic signature for heart failure with preserved ejection fraction (HFpEF): a machine learning approach using multi-modality electronic health record data.

BACKGROUND: Heart failure with preserved ejection fraction (HFpEF) is thought to be highly prevalent yet remains underdiagnosed. Evidence-based treatments are available that increase quality of life and decrease hospitalization. We sought to develop a data-driven diagnostic model to predict from electronic health records (EHR) the likelihood of HFpEF among patients with unexplained dyspnea and preserved left ventricular EF. METHODS AND RESULTS: The derivation cohort comprised patients with dyspnea and echocardiography results. Structured and unstructured data were extracted using an automated informatics pipeline. Patients were retrospectively diagnosed as HFpEF (cases), non-HF (control cohort I), or HF with reduced EF (HFrEF; control cohort II). The ability of clinical parameters and investigations to discriminate cases from controls was evaluated by extreme gradient boosting. A likelihood scoring system was developed and validated in a separate test cohort. The derivation cohort included 1585 consecutive patients: 133 cases of HFpEF (9%), 194 non-HF cases (Control cohort I) and 1258 HFrEF cases (Control cohort II). Two HFpEF diagnostic signatures were derived, comprising symptoms, diagnoses and investigation results. A final prediction model was generated based on the averaged likelihood scores from these two models. In a validation cohort consisting of 269 consecutive patients [with 66 HFpEF cases (24.5%)], the diagnostic power of detecting HFpEF had an AUROC of 90% (P < 0.001) and average precision of 74%. CONCLUSION: This diagnostic signature enables discrimination of HFpEF from non-cardiac dyspnea or HFrEF from EHR and can assist in the diagnostic evaluation in patients with unexplained dyspnea. This approach will enable identification of HFpEF patients who may then benefit from new evidence-based therapies.

Pre-existing cardiovascular disease rather than cardiovascular risk factors drives mortality in COVID-19.

BACKGROUND: The relative association between cardiovascular (CV) risk factors, such as diabetes and hypertension, established CV disease (CVD), and susceptibility to CV complications or mortality in COVID-19 remains unclear. METHODS: We conducted a cohort study of consecutive adults hospitalised for severe COVID-19 between 1st March and 30th June 2020. Pre-existing CVD, CV risk factors and associations with mortality and CV complications were ascertained. RESULTS: Among 1721 patients (median age 71 years, 57% male), 349 (20.3%) had pre-existing CVD (CVD), 888 (51.6%) had CV risk factors without CVD (RF-CVD), 484 (28.1%) had neither. Patients with CVD were older with a higher burden of non-CV comorbidities. During follow-up, 438 (25.5%) patients died: 37% with CVD, 25.7% with RF-CVD and 16.5% with neither. CVD was independently associated with in-hospital mortality among patients < 70 years of age (adjusted HR 2.43 [95% CI 1.16-5.07]), but not in those ≥ 70 years (aHR 1.14 [95% CI 0.77-1.69]). RF-CVD were not independently associated with mortality in either age group (< 70 y aHR 1.21 [95% CI 0.72-2.01], ≥ 70 y aHR 1.07 [95% CI 0.76-1.52]). Most CV complications occurred in patients with CVD (66%) versus RF-CVD (17%) or neither (11%; p < 0.001). 213 [12.4%] patients developed venous thromboembolism (VTE). CVD was not an independent predictor of VTE. CONCLUSIONS: In patients hospitalised with COVID-19, pre-existing established CVD appears to be a more important contributor to mortality than CV risk factors in the absence of CVD. CVD-related hazard may be mediated, in part, by new CV complications. Optimal care and vigilance for destabilised CVD are essential in this patient group. Trial registration n/a.

In response to Ballantyne and Schaefer's 'Consent and the ethical duty to participate in health data research'.

We welcome Ballantyne & Schaefer's discussion of the issues concerning consent and use of health data for research. In response to their acknowledgement of the need for public debate and discussion, we provide evidence from our own public consultation on this topic.

Late cortical plasticity in motor and auditory cortex: role of met-allele in BDNF Val66Met polymorphism.

The brain-derived neurotropic factor (BDNF) Val66Met polymorphism has been associated with abnormalities of synaptic plasticity in animal models, and abnormalities in motor cortical plasticity have also been described in humans using transcranial direct current stimulation. No study has yet been done on plasticity in non-motor regions, and the effect of two Met alleles (i.e. 'Met dose') is not well understood. We studied the effect of the BDNF Val66Met polymorphism on the after-effects of transcranial direct current stimulation and tetanic auditory stimulation in 65 subjects (23; Val66Val, 22; Val66Met and 20; Met66Met genotypes). In the first session, motor evoked potentials (MEP) were recorded under stereotaxic guidance for 90 min after 9 min of anodal transcranial direct current stimulation (TDCS). In the second session, auditory-evoked potentials (AEP) were recorded before and after 2 min of auditory 13 Hz tetanic stimulation. There was a difference in MEP facilitation post-TDCS comparing Met carriers with non-Met carriers, with Met carriers having a modest late facilitation at 30-90 min. There was no difference in responses between Val66Met genotype and Met66Met genotype subjects. Tetanic auditory stimulation also produced late facilitation of N1-P2 AEP at 25 min, but there was no apparent effect of genetic status. This study indicates that Met66Met carriers behave like Val66Met carriers for TDCS-induced plasticity, and produce a late facilitation of MEPs. Auditory cortical plasticity was not affected by the BDNF Val66Met polymorphism. This study sheds light on the differences between auditory and motor cortical plasticity and the role of the BDNF Val66Met polymorphism.

Cerebellar theta burst stimulation impairs eyeblink classical conditioning.

Theta burst stimulation (TBS) protocols of repetitive transcranial magnetic stimulation (rTMS) have after-effects on excitability of motor areas thought to be due to LTP- and LTD-like processes at cortical synapses. The present experiments ask whether, despite the low intensities of stimulation used and the anatomy of the posterior fossa, TBS can also influence the cerebellum. Acquisition and retention of eyeblink classical conditioning (EBCC) was examined in 30 healthy volunteers after continuous theta burst stimulation (cTBS) over the right cerebellar hemisphere. In subjects who received cerebellar cTBS, conditioned responses were fewer and their onsets were earlier (in the last half of the acquisition blocks) than those from control subjects. There was, however, no effect of cerebellar cTBS on the re-acquisition of EBCC in another session of EBCC 7­10 days later. There was also no effect of cerebellar cTBS on the re-acquisition of EBCC in subjects not naïve to EBCC when the stimulation was delivered immediately before a re-acquisition session. Control experiments verified that suppressive effects of cTBS on EBCC were not due to changes in motor cortical excitability or sensory disturbance caused by cTBS. Based on previous EBCC studies in various cerebellar pathologies, our data are compatible with the hypothesis that cerebellar cTBS has a focal cerebellar cortical effect, and are broadly in line with data from studies of EBCC in various animal models. These results confirm that cerebellar TBS has measurable effects on the function of the cerebellum, and indicate it is a useful non-invasive technique with which to explore cerebellar physiology and function in humans.

Human θ burst stimulation enhances subsequent motor learning and increases performance variability.

Intermittent theta burst stimulation (iTBS) transiently increases motor cortex excitability in healthy humans by a process thought to involve synaptic long-term potentiation (LTP), and this is enhanced by nicotine. Acquisition of a ballistic motor task is likewise accompanied by increased excitability and presumed intracortical LTP. Here, we test how iTBS and nicotine influences subsequent motor learning. Ten healthy subjects participated in a double-blinded placebo-controlled trial testing the effects of iTBS and nicotine. iTBS alone increased the rate of learning but this increase was blocked by nicotine. We then investigated factors other than synaptic strengthening that may play a role. Behavioral analysis and modeling suggested that iTBS increased performance variability, which correlated with learning outcome. A control experiment confirmed the increase in motor output variability by showing that iTBS increased the dispersion of involuntary transcranial magnetic stimulation-evoked thumb movements. We suggest that in addition to the effect on synaptic plasticity, iTBS may have facilitated performance by increasing motor output variability; nicotine negated this effect on variability perhaps via increasing the signal-to-noise ratio in cerebral cortex.

Real-time clinician text feeds from electronic health records.

Analyses of search engine and social media feeds have been attempted for infectious disease outbreaks, but have been found to be susceptible to artefactual distortions from health scares or keyword spamming in social media or the public internet. We describe an approach using real-time aggregation of keywords and phrases of freetext from real-time clinician-generated documentation in electronic health records to produce a customisable real-time viral pneumonia signal providing up to 4 days warning for secondary care capacity planning. This low-cost approach is open-source, is locally customisable, is not dependent on any specific electronic health record system and can provide an ensemble of signals if deployed at multiple organisational scales.

Biological responses to COVID-19: Insights from physiological and blood biomarker profiles.

BACKGROUND: Understanding the spectrum and course of biological responses to coronavirus disease 2019 (COVID-19) may have important therapeutic implications. We sought to characterise biological responses among patients hospitalised with severe COVID-19 based on serial, routinely collected, physiological and blood biomarker values. METHODS AND FINDINGS: We performed a retrospective cohort study of 1335 patients hospitalised with laboratory-confirmed COVID-19 (median age 70 years, 56 % male), between 1st March and 30th April 2020. Latent profile analysis was performed on serial physiological and blood biomarkers. Patient characteristics, comorbidities and rates of death and admission to intensive care, were compared between the latent classes. A five class solution provided the best fit. Class 1 "Typical response" exhibited a moderately elevated and rising C-reactive protein (CRP), stable lymphopaenia, and the lowest rates of 14-day adverse outcomes. Class 2 "Rapid hyperinflammatory response" comprised older patients, with higher admission white cell and neutrophil counts, which declined over time, accompanied by a very high and rising CRP and platelet count, and exibited the highest mortality risk. Class 3 "Progressive inflammatory response" was similar to the typical response except for a higher and rising CRP, though similar mortality rate. Class 4 "Inflammatory response with kidney injury" had prominent lymphopaenia, moderately elevated (and rising) CRP, and severe renal failure. Class 5 "Hyperinflammatory response with kidney injury" comprised older patients, with a very high and rising CRP, and severe renal failure that attenuated over time. Physiological measures did not substantially vary between classes at baseline or early admission. CONCLUSIONS AND RELEVANCE: Our identification of five distinct classes of biomarker profiles provides empirical evidence for heterogeneous biological responses to COVID-19. Early hyperinflammatory responses and kidney injury may signify unique pathophysiology that requires targeted therapy.

Excess deaths in people with cardiovascular diseases during the COVID-19 pandemic.

AIMS: Cardiovascular diseases (CVDs) increase mortality risk from coronavirus infection (COVID-19). There are also concerns that the pandemic has affected supply and demand of acute cardiovascular care. We estimated excess mortality in specific CVDs, both 'direct', through infection, and 'indirect', through changes in healthcare. METHODS AND RESULTS: We used (i) national mortality data for England and Wales to investigate trends in non-COVID-19 and CVD excess deaths; (ii) routine data from hospitals in England (n = 2), Italy (n = 1), and China (n = 5) to assess indirect pandemic effects on referral, diagnosis, and treatment services for CVD; and (iii) population-based electronic health records from 3 862 012 individuals in England to investigate pre- and post-COVID-19 mortality for people with incident and prevalent CVD. We incorporated pre-COVID-19 risk (by age, sex, and comorbidities), estimated population COVID-19 prevalence, and estimated relative risk (RR) of mortality in those with CVD and COVID-19 compared with CVD and non-infected (RR: 1.2, 1.5, 2.0, and 3.0).Mortality data suggest indirect effects on CVD will be delayed rather than contemporaneous (peak RR 1.14). CVD service activity decreased by 60-100% compared with pre-pandemic levels in eight hospitals across China, Italy, and England. In China, activity remained below pre-COVID-19 levels for 2-3 months even after easing lockdown and is still reduced in Italy and England. For total CVD (incident and prevalent), at 10% COVID-19 prevalence, we estimated direct impact of 31 205 and 62 410 excess deaths in England (RR 1.5 and 2.0, respectively), and indirect effect of 49 932 to 99 865 deaths. CONCLUSION: Supply and demand for CVD services have dramatically reduced across countries with potential for substantial, but avoidable, excess mortality during and after the pandemic.

Angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers are not associated with severe COVID-19 infection in a multi-site UK acute hospital trust.

AIMS: The SARS-CoV-2 virus binds to the angiotensin-converting enzyme 2 (ACE2) receptor for cell entry. It has been suggested that angiotensin-converting enzyme inhibitors (ACEi) and angiotensin II receptor blockers (ARB), which are commonly used in patients with hypertension or diabetes and may raise tissue ACE2 levels, could increase the risk of severe COVID-19 infection. METHODS AND RESULTS: We evaluated this hypothesis in a consecutive cohort of 1200 acute inpatients with COVID-19 at two hospitals with a multi-ethnic catchment population in London (UK). The mean age was 68 ± 17 years (57% male) and 74% of patients had at least one comorbidity. Overall, 415 patients (34.6%) reached the primary endpoint of death or transfer to a critical care unit for organ support within 21 days of symptom onset. A total of 399 patients (33.3%) were taking ACEi or ARB. Patients on ACEi/ARB were significantly older and had more comorbidities. The odds ratio for the primary endpoint in patients on ACEi and ARB, after adjustment for age, sex and co-morbidities, was 0.63 (95% confidence interval 0.47-0.84, P < 0.01). CONCLUSIONS: There was no evidence for increased severity of COVID-19 in hospitalised patients on chronic treatment with ACEi or ARB. A trend towards a beneficial effect of ACEi/ARB requires further evaluation in larger meta-analyses and randomised clinical trials.

A case-control and cohort study to determine the relationship between ethnic background and severe COVID-19.

BACKGROUND: People of minority ethnic backgrounds may be disproportionately affected by severe COVID-19. Whether this relates to increased infection risk, more severe disease progression, or worse in-hospital survival is unknown. The contribution of comorbidities or socioeconomic deprivation to ethnic patterning of outcomes is also unclear. METHODS: We conducted a case-control and a cohort study in an inner city primary and secondary care setting to examine whether ethnic background affects the risk of hospital admission with severe COVID-19 and/or in-hospital mortality. Inner city adult residents admitted to hospital with confirmed COVID-19 (n = 872 cases) were compared with 3,488 matched controls randomly sampled from a primary healthcare database comprising 344,083 people residing in the same region. For the cohort study, we studied 1827 adults consecutively admitted with COVID-19. The primary exposure variable was self-defined ethnicity. Analyses were adjusted for socio-demographic and clinical variables. FINDINGS: The 872 cases comprised 48.1% Black, 33.7% White, 12.6% Mixed/Other and 5.6% Asian patients. In conditional logistic regression analyses, Black and Mixed/Other ethnicity were associated with higher admission risk than white (OR 3.12 [95% CI 2.63-3.71] and 2.97 [2.30-3.85] respectively). Adjustment for comorbidities and deprivation modestly attenuated the association (OR 2.24 [1.83-2.74] for Black, 2.70 [2.03-3.59] for Mixed/Other). Asian ethnicity was not associated with higher admission risk (adjusted OR 1.01 [0.70-1.46]). In the cohort study of 1827 patients, 455 (28.9%) died over a median (IQR) of 8 (4-16) days. Age and male sex, but not Black (adjusted HR 1.06 [0.82-1.37]) or Mixed/Other ethnicity (adjusted HR 0.72 [0.47-1.10]), were associated with in-hospital mortality. Asian ethnicity was associated with higher in-hospital mortality but with a large confidence interval (adjusted HR 1.71 [1.15-2.56]). INTERPRETATION: Black and Mixed ethnicity are independently associated with greater admission risk with COVID-19 and may be risk factors for development of severe disease, but do not affect in-hospital mortality risk. Comorbidities and socioeconomic factors only partly account for this and additional ethnicity-related factors may play a large role. The impact of COVID-19 may be different in Asians. FUNDING: British Heart Foundation; the National Institute for Health Research; Health Data Research UK.

Prolonged cortical silent period but normal sensorimotor plasticity in spinocerebellar ataxia 6.

Spinocerebellar ataxia 6 (SCA6) is a hereditary disease characterized by a trinucleotide repeat expansion in the CACNA1A gene and late-onset bilateral cerebellar atrophy. It is unclear if there is significant pathology outside of the cerebellum. We used transcranial magnetic stimulation to assess sensorimotor cortical circuits and cortical plasticity in 8 SCA6 patients and 8 age-matched controls. Behavioral performance was assessed using a rhythmic tapping task. Neurophysiological measures of SCA6 patients showed a prolonged cortical silent period (CSP) but normal MEP recruitment curve, short-latency afferent inhibition, long-latency afferent inhibition and ipsilateral silent period. Paired-associative stimulation induction also increased motor-evoked potentials normally. SCA6 patients had greater variability with cued rhythmic tapping than normals and deteriorated when the cue was removed; in comparison, normal subjects had similar variability between cued and uncued rhythmic tapping. Analysis using a Wing-Kristofferson timing model indicated that both clock variance and motor delay variance were abnormal. Conclusion. In SCA6, the circuits for sensorimotor integration and the mechanisms for LTP-like plasticity in the sensorimotor cortex are unimpaired. A prolonged CSP in SCA6 just like in other cerebellar atrophies would suggest that this neurophysiological change typifies cerebellar dysfunction.

Selective impairment of sadness and disgust recognition in abstinent ecstasy users.

Previous data have suggested that ecstasy use may affect cognitive functions. The relationship between ecstasy use and emotion recognition remains largely unknown. This study reports the findings on the neuropsychological effects of ecstasy use on recognition of basic human emotions among 100 abstinent ecstasy users, along with 100 demographically matched nonusers. Recognition of both facial and prosodic emotions was studied. In addition, neuropsychological predictors of emotion recognition for abstinent ecstasy users were examined. The results showed that abstinent ecstasy users were impaired, relative to nonusers, on overall emotion recognition. In particular, recognition of sadness and disgust was significantly affected. The emotion-recognition deficits observed among the abstinent ecstasy users may reflect a complex derangement of monoamines and/or general degenerative change observed in the addicted populations. The length of time in months since ecstasy was last consumed, cumulative ecstasy dosage, and years of education negatively predicted various domains of emotion recognition. The observation that nonverbal and verbal fluency functions were significant predictors of emotion identification, as well as of recognition of sadness and disgust, suggests that the frontal executive system might be affected by ecstasy use.

Effect of ecstasy use on neuropsychological function: a study in Hong Kong.

RATIONALE: Previous studies on the effects of ecstasy on neuropsychological performance have often recruited small sample sizes. OBJECTIVES: The present study was conducted to validate previous findings regarding the effects of ecstasy consumption on neuropsychological performance. METHOD: A comprehensive neuropsychological investigation was conducted in 100 abstinent ecstasy users and 100 matched non-user counterparts on standardized measures of working memory, verbal and non-verbal memory, verbal and figural fluency, and selective and switching attention. RESULTS: Abstinent ecstasy users were impaired on verbal and non-verbal memory, complex attention, and verbal fluency, but not on working memory, relative to their non-user counterparts. Of particular interest was the fact that abstinent ecstasy users performed better on figural fluency relative to their non-user counterparts. In addition, only cumulative ecstasy consumption correlated with neuropsychological performances among abstinent ecstasy users. Canonical discriminant analysis yielded verbal and visual memory, switching attention, and verbal fluency as potential core neuropsychological variables for differentiating abstinent ecstasy users from non-users. Levels of depression and general non-verbal intelligence, as measured by the Beck Depression Inventory and the test of non-verbal Intelligence, respectively, were not likely to affect these findings, since these measures were matched between ecstasy users and non-users. CONCLUSIONS: These findings suggest that previous ecstasy consumption can affect a wide range of neuropsychological performance, though figural fluency may be subsequently enhanced as a result of the phenomenon of "cortical disinhibition." Furthermore, measures of verbal and visual memory, switching attention, and verbal fluency may be particularly useful for differentiating abstinent ecstasy users from non-users.

Differential impairment on measures of attention in patients with paranoid and nonparanoid schizophrenia.

The purpose of the present study is to investigate whether patients with different subtypes of schizophrenia are differentially impaired on measures of attention. Forty-eight patients with schizophrenia (19 paranoid and 29 nonparanoid) and 48 healthy controls (matched on chronological age, sex, and years of education) were administered five measures of attention including the Stroop Color-Word Test (SCWT; Stroop, 1935), the Digit Vigilance Test (DVT; Lewis, 1992), the Symbol Digit Modalities Test (SDMT; Smith, 1982), the Backward Digit Span Test (BDST; Wechsler, 1987), and the Color Trails Test (CTT; D'Elia et al., 1996) to assess selective attention, sustained attention, switching attention, and attentional control processing by the latter two tests respectively. Results from the present study showed that patients with schizophrenia performed poorer on the SCWT, the DVT, and the SDMT, relative to their healthy counterparts. Furthermore, patients with different subtypes of schizophrenia also had different degrees of attentional impairment. While patients with paranoid schizophrenia performed worse on the SCWT, those with nonparanoid schizophrenia performed worse on the SDMT. Nevertheless, these findings may suggest that patients with paranoid and nonparanoid schizophrenia may have different profiles with respect to their performances on measures of attention.

Detection of cervical metastasis. A meta-analysis comparing computed tomography with physical examination.

BACKGROUND: Despite extensive coverage in recent literature, controversy continues with regard to the relative sensitivities of computed tomography (CT) and physical examination (PE). OBJECTIVE: To identify a statistically significant consensus. DATA SOURCES: Initially, data were reviewed on 47 consecutive patients with head and neck cancer on whom a total of 53 neck dissections were performed. These data were combined with findings from a 15-year MEDLINE review of the English-language literature, including references. STUDY SELECTION: All publications that contained a direct comparison of CT with PE, with appropriate data availability, were included. DATA EXTRACTION: Multiple-observer independent extraction was used. A total of 647 neck dissections were included in the meta-analysis. The definition of metastasis varied minimally among studies as follows: (1) nodal size, greater than 10 to 15 mm; (2) multiplicity of 8- to 10-mm nodes; or (3) evidence of necrosis. Necks were compared for positivity or negativity rather than for the actual nodal staging. In all cases, a final determination was made by results of histopathologic examination of surgical specimens. DATA SYNTHESES: The results in this review favored CT over PE but were not statistically significant by use of the Fisher exact test. A combination of the present study's data with those of the literature review yielded the following meta-analysis results: sensitivity, 83% (CT) vs 74% (PE) (P = .002); specificity, 83% (CT) vs 81% (PE) (P = .7); and accuracy, 83% (CT) vs 77% (PE) (P = .006). Overall, PE identified 75% of pathologic cervical adenopathy; this detection rate increased to 91% with the addition of CT. The results of sensitivity analysis confirmed homogeneity across study designs. CONCLUSIONS: Computed tomography is a more sensitive indicator of cervical metastasis than PE. More importantly, these diagnostic modalities were additive, with CT significantly enhancing the detection rates of PE alone. All patients who are at risk for cervical metastasis should have CT or equivalent radiographic imaging performed prior to therapeutic intervention. Future studies correlating CT detection rates to the primary site and staging are needed before more specific conclusions can be drawn.

Atypical Parkinsonism-Dystonia Syndrome Caused by a Novel DJ1 Mutation.

We describe a sporadic case of atypical parkinsonism-dystonia of subacute onset at the age of 16 years in a male from a consanguineous family. He showed marked orofacial dystonia, levodopa-induced dyskinesia, and a stereotyped bilateral eye-pressing movement disorder. We combined Sanger sequencing of candidate genes, homozygosity mapping, and whole-exome sequencing. A homozygous mutation was identified disrupting a splice site in exon 5 of the DJ1 (PARK7) gene. Clinical details and a video are provided. DJ1 mutations are a rare cause of atypical complex parkinsonism. Exome sequencing is efficacious in identifying the causal gene variant.