About

Allison Willis, MD, MS, is a Professor of Neurology at the University of Pennsylvania. She serves as an Attending Neurologist within the University of Pennsylvania Health System and holds multiple faculty scholar positions, including at the Center for Clinical Epidemiology and Biostatistics, the Institute of Aging, and the Leonard Davis Institute of Health Economics at the University of Pennsylvania Perelman School of Medicine. Dr. Willis is also the Co-Director of the Resource Center for Minority Aging Research and the Associate Chief of Staff for Neurology at the Corporal Michael J. Crescenz VA Medical Center. Her research focuses on health equity, aging, and neurological conditions, with a particular interest in deprescribing measures, medication burden, and health outcomes in neurodegenerative diseases. She is actively involved in advancing clinical epidemiology and health services research related to aging and neurological health.

Research topics

• Medicine
• Internal medicine
• Psychiatry
• Gerontology
• Pathology
• Political Science
• Physical therapy
• Pediatrics
• Demography
• Environmental health
• Anesthesia
• Family medicine
• Bioinformatics
• Surgery

Selected publications

• Plain Language Summary Publication: Perceived discrimination and migraine‐specific quality of life: A cross‐sectional survey study in a Black/African American sample

  Headache The Journal of Head and Face Pain · 2025-08-08

  articleOpen access

  Mara Getz, Larry Charleston IV, Cynthia E. Armand, Allison W. Willis, and Elizabeth Seng declare no conflicts of interest.

  PublisherOA PDFDOI

• Perceived discrimination and migraine‐specific quality of life: A cross‐sectional survey study in a Black/African American sample

  Headache The Journal of Head and Face Pain · 2025-06-02 · 4 citations

  articleOpen access

  OBJECTIVE: To examine the associations between perceived lifetime discrimination and discrimination in medical settings with migraine-specific quality of life in Black/African Americans with migraine. BACKGROUND: Perceived discrimination negatively impacts health outcomes and quality of life, particularly in minoritized populations. African Americans with migraine disease face compounded challenges due to limited access to specialized treatments and discrimination in medical settings, leading to disparities in migraine care and outcomes. However, few studies have investigated how perceived discrimination affects migraine-specific quality of life in this population. This study evaluated whether higher levels of perceived lifetime discrimination and discrimination in medical settings were associated with worse migraine-specific quality of life in Black/African Americans with migraine. METHODS: Black/African American adults with a migraine diagnosis (N = 91) were recruited from a tertiary headache center between October 2023 and April 2024 for this cross-sectional study. Participants underwent testing using validated research tools to measure migraine-specific quality of life (Migraine-Specific Quality-of-Life Questionnaire), lifetime perceived discrimination (Perceived Ethnic Discrimination Questionnaire-Community Version [PEDQ-CV]), and discrimination in medical settings (Discrimination in Medical Settings Scale [DMS]). Headache frequency and pain intensity were assessed via Migraine Disability Assessment items (MIDAS Item A and B). Associations between discrimination measures and migraine-specific quality of life, controlling for headache pain, frequency, and sex at birth were examined. RESULTS: Higher levels of lifetime perceived discrimination and discrimination in medical settings were significantly associated with worse migraine-specific quality of life (PEDQ-CV: β = -0.30, p = 0.004, 95% confidence interval [CI] -0.49 to -0.10; DMS: β = -0.27, p = 0.016, 95% CI -0.47 to -0.06), independent of headache frequency and sex at birth. Headache pain intensity was also significantly associated with poorer quality of life across models (β = -0.43, p < 0.001, 95% CI -0.63 to -0.23). Headache frequency and sex at birth were not significantly associated with outcomes. Together, discrimination measures and pain intensity accounted for 28.3-31.6% of the variance in migraine-specific quality of life. CONCLUSIONS: Experiences of discrimination, both across the lifetime and within the medical setting, significantly impact migraine-specific quality of life in Black/African Americans. These findings highlight the critical need for interventions that reduce bias in migraine care, improve pain management, and address the psychosocial stress linked to discrimination. Future research should focus on investigating the pathways through which discrimination exacerbates health disparities and on developing multidisciplinary, culturally competent strategies to improve care and reduce inequities for minoritized populations.

  PublisherOA PDFDOI

• Impact of pimavanserin on prescribing practices in parkinson disease

  Clinical Parkinsonism & Related Disorders · 2025-01-01 · 2 citations

  articleOpen accessSenior author

  • Parkinson disease psychosis (PDP) is a common complication in later stages of PD. • Antipsychotics (APs) with dopamine receptor antagonism (DRA) may worsen PD symptoms. • Pimavanserin is a selective serotonin reverse agonist/antagonist with no known DRA. • Use of mixed-receptor-high-DRA APs declined after pimavanserin’s introduction. • Quetiapine, a mixed-receptor-low-DRA AP, remained the most prescribed AP for PDP. Parkinson disease psychosis (PDP) is a common complication of PD. Until 2016, the only drugs available to treat PDP in the U.S. were antipsychotics with variable degrees of dopamine-receptor antagonism (DRA) that may worsen PD motor symptoms. We evaluated the impact that pimavanserin, a selective serotonin receptor inverse agonist/antagonist atypical antipsychotic (AAP) with no known DRA, had on PDP treatment practices in a commercially insured population. We included adults diagnosed with PD who filled at least one AAP prescription from 2016 to 2022. AAP dispensings were categorized into (1) pimavanserin, (2) clozapine and quetiapine (i.e., PDP-“preferred” mixed receptor antagonist AAPs), and (3) the remaining AAPs (i.e., PDP-“nonpreferred” mixed receptor antagonist AAPs). Trends in quarterly dispensing rates per 1000 persons treated were compared across categories. Secondary analyses focused on the 65+ subpopulations insured by Medicare Advantage programs. Dispensing rates varied between 4 and 697/1000 persons treated for pimavanserin, 1434–1821 for preferred, and 394–746 for nonpreferred AAPs. Pimavanserin dispensings surpassed the nonpreferred category after quarter 3 of 2018. However, preferred AAPs, particularly quetiapine, remained the most dispensed category in the sixth year after pimavanserin’s approval. We observed similar trends among Medicare Advantage enrollees. The availability of pimavanserin was followed by a decline in the use of the most harmful AAPs in persons living with PD. Quetiapine remained the most prescribed AAP. Comparative safety and effectiveness studies are needed to define the relative risks and benefits of treatment options in PDP.

  PublisherDOI

• Impact of Anticholinergic Burden and Clinical-Demographic Characteristics on Incident Dementia in Parkinson Disease

  Journal of Geriatric Psychiatry and Neurology · 2025-01-07 · 2 citations

  articleOpen accessSenior author

  PurposeAnticholinergic medication use measured via the Anticholinergic Cognitive Burden (ACB) scale has been associated with an increased dementia incidence in older adults but has not been explored specifically for Parkinson disease dementia (PDD). We used adjusted Cox models to estimate the risk of incident PDD associated with demographic factors, clinical characteristics, and time-varying total ACB in a longitudinal, deeply-phenotyped prospective PD cohort.Major findings56.5% of study participants were taking ACB-scale drugs at enrollment. Increasing age, motor symptom burden and psychosis were associated with PDD risk. Female sex and educational achievement were protective against PDD. ACB categories were not associated with PDD overall, but depression and impulse control disorder were strongly associated with PDD in a subsample with high baseline ACB.ConclusionsPatient and clinical factors modify PDD risk. PD drug safety and drug-disease interaction studies may require considering multiple mechanisms and including dose-based, prospectively acquired medication exposure measures.

  PublisherOA PDFDOI

• Comorbidity Risk Assessment in Medicare Beneficiaries with Neurodevelopmental Disorders

  Innovation in Aging · 2025-12-01

  articleOpen accessSenior author

  Abstract Neurodevelopmental disorders (NDDs) are lifelong conditions that affect brain development and functioning, with varying levels of impairment on daily life. Advances in technology have extended life expectancy for individuals with NDDs; however, little is known about their health in older adulthood. Using a 20% random sample of Medicare beneficiaries in 2021, we identified adults aged 65 and older with autism spectrum disorder, cerebral palsy, muscular dystrophy, or spina bifida. Demographic characteristics and comorbidities were compared to a control group without NDDs. Compared with controls, older adults with NDDs were younger on entry into Medicare, had distinct sex distributions, and were less racially and ethnically diverse. Neurological conditions—including epilepsy, multiple sclerosis, and migraine—were markedly more prevalent among NDD groups, as were psychiatric disorders such as anxiety, depression, and psychosis. Substance use disorders, particularly alcohol abuse and dependence, occurred at nearly twice the rate of controls. Vascular conditions, including myocardial infarction, atrial fibrillation, heart failure, ischemic heart disease, and stroke, were also elevated, averaging twofold higher in NDD groups. Neurodegenerative diseases, notably Alzheimer’s dementia and Parkinson’s disease, were up to three times more common among individuals aging with NDDs, underscoring the dual impact of lifelong neurodevelopmental conditions and aging-related decline. These findings demonstrate that while vascular and substance use disorders contribute to the excess burden of disease, the most pronounced disparities lie in neurological, psychiatric, and neurodegenerative comorbidities. This highlights the urgent need for research on neurodegeneration risk in NDD populations and for healthcare adaptations to better support individuals with lifelong NDDs.

  PublisherOA PDFDOI

• Examining the effects of race/ethnicity and other factors on outcomes of care for complex regional pain syndrome type 1 in the United States

  PLOS Global Public Health · 2025-01-08

  articleOpen accessCorresponding

  Complex regional pain syndrome is a chronic pain disorder marked by symptoms such as swelling, impaired motor function, and sympathetic dysfunction. Our primary objective was to determine the total number of complex regional pain syndrome type 1 (CRPS-1) emergency department (ED) visits and hospitalizations by race/ethnicity, as well as to assess sex and age distributions by race/ethnicity. Secondary objectives were to examine whether race/ethnicity, as well as select characteristics, are associated with hospitalization and longer length of stay. We completed a cross-sectional study of adults (19+ years) using acute and inpatient care data from the 2020 Nationwide Emergency Department Sample and the National Inpatient Sample. The overall rate of CRPS-1 diagnosis among ED visits and hospitalizations was 0.02% and 0.04%, respectively. Most CRPS-1 care was provided to White (ED: 83.1%; inpatient: 82.8%) patients. Within race/ethnicity groups, CRPS-1 ED visits and hospitalizations generally increased with age. Secondary findings included: 1) ED visits by Black individuals (compared with White) were significantly negatively associated with immediate hospitalization (adjusted odds ratio (AOR) 0.74, 95% CI 0.55 to 0.99); 2) hospitalizations by Black patients (compared with White) were independently associated with increased length of stay (odds ratio (OR) 1.45, 95% CI 1.07 to 1.96), though the association diminished with adjustment; and 3) drug abuse was significantly associated with hospitalization (AOR 4.67, 95% CI 3.53 to 6.18) and longer length of stay (AOR 1.81, 95% CI 1.34 to 2.46). Race/ethnicity was minimally associated with studied CRPS-1 outcomes. Additional studies are required to determine the impact of race/ethnicity on seeking care for CRPS-1.

  PublisherOA PDFDOI

• Comparing retrospective informant assessments to prospectively collected cognitive measures in the Health and Retirement Study

  Alzheimer s & Dementia Diagnosis Assessment & Disease Monitoring · 2025-07-01 · 1 citations

  articleOpen access

  Abstract INTRODUCTION Clinicians and researchers frequently ask informants about changes in a person's cognition, but whether informant assessments correspond to objectively measured change is unclear. METHODS A subset ( n = 2710) of US Health and Retirement Study participants and their informants completed the Harmonized Cognitive Assessment Protocol (HCAP). Using generalized estimating equations, we compared informant‐reported change in memory and daily functioning to prospectively collected delayed word recall and instrumental activities of daily living (iADL) in the 10 years preceding HCAP. RESULTS Informant reports of worsened memory were associated with declining word recall, and informant‐reported iADL loss was associated with declining iADLs. Informant‐reported memory impairment was more strongly associated with declining word recall when informants saw the respondent weekly or more compared to one to three times monthly or less ( p &lt; 0.0001 for interaction). DISCUSSION Informant assessments of memory and iADLs are generally consistent with prospective measurements, but this relationship depends significantly on frequency of informant contact. Highlights Informant ratings of a person's memory and daily functioning are generally reliable. Quality of reporting depends on frequency of informant contact. Knowing an informant's characteristics is important for interpreting responses.

  PublisherOA PDFDOI

• Genetic and phenotypic characterization of Parkinson’s disease at the clinic-wide level

  npj Parkinson s Disease · 2024-05-03 · 11 citations

  articleOpen access

  Observational studies in Parkinson's disease (PD) deeply characterize relatively small numbers of participants. The Molecular Integration in Neurological Diagnosis Initiative seeks to characterize molecular and clinical features of every PD patient at the University of Pennsylvania (UPenn). The objectives of this study are to determine the feasibility of genetic characterization in PD and assess clinical features by sex and GBA1/LRRK2 status on a clinic-wide scale. All PD patients with clinical visits at the UPenn PD Center between 9/2018 and 12/2022 were eligible. Blood or saliva were collected, and a clinical questionnaire administered. Genotyping at 14 GBA1 and 8 LRRK2 variants was performed. PD symptoms were compared by sex and gene groups. 2063 patients were approached and 1,689 (82%) were enrolled, with 374 (18%) declining to participate. 608 (36%) females were enrolled, 159 (9%) carried a GBA1 variant, and 44 (3%) carried a LRRK2 variant. Compared with males, females across gene groups more frequently reported dystonia (53% vs 46%, p = 0.01) and anxiety (64% vs 55%, p < 0.01), but less frequently reported cognitive impairment (10% vs 49%, p < 0.01) and vivid dreaming (53% vs 60%, p = 0.01). GBA1 variant carriers more frequently reported anxiety (67% vs 57%, p = 0.04) and depression (62% vs 46%, p < 0.01) than non-carriers; LRRK2 variant carriers did not differ from non-carriers. We report feasibility for near-clinic-wide enrollment and characterization of individuals with PD during clinical visits at a high-volume academic center. Clinical symptoms differ by sex and GBA1, but not LRRK2, status.

  PublisherOA PDFDOI

• Attitudes and beliefs towards medication burden and deprescribing in Parkinson disease

  BMC Neurology · 2024-09-06 · 4 citations

  articleOpen accessSenior author

  BACKGROUND: Deprescribing of potentially inappropriate medications is recommended for older adults and may improve health outcomes and quality of life in persons living with Parkinson disease (PD). Patient attitudes, beliefs, and preferences play a crucial role in the success of deprescribing interventions. We aimed to examine the attitudes and beliefs about medication burden and deprescribing among persons living with PD. METHODS: We administered a survey to participants of Fox Insight, a prospective longitudinal study of persons living with PD. The survey included the revised Patients' Attitudes Towards Deprescribing (rPATD) questionnaire and additional questions about adverse drug effects. We used logistic regression models to explore potential predictors of treatment dissatisfaction and willingness to deprescribe. RESULTS: Of the 4945 rPATD respondents, 31.6% were dissatisfied with their current medications, and 87.1% would be willing to deprescribe medications. Male sex was associated with a greater willingness to deprescribe (adjusted odds ratio [aOR] 1.62, 95% confidence interval [CI] 1.37-1.93). A greater belief that the medication burden was high or that some medications were inappropriate was associated with treatment dissatisfaction (aORs 3.74, 95% CI 3.26-4.29 and 5.61, 95% CI 4.85-6.50), and more willingness to deprescribe (aORs 1.74, 95% CI 1.47-2.06 and 2.87, 95% CI 2.41-3.42). Cognitive impairment was the adverse drug effect participants were most concerned about when prescribed new medications to treat nonmotor symptoms. CONCLUSIONS: Persons with PD are often dissatisfied with their overall medication load and are open to deprescribing. Medications that are associated with cognitive impairment might be prioritized targets for deprescribing interventions in this population.

  PublisherOA PDFDOI

• Direct-Acting Oral Anticoagulants and Antiseizure Medications for Atrial Fibrillation and Epilepsy and Risk of Thromboembolic Events

  JAMA Neurology · 2024-07-08 · 14 citations

  article

  Importance: Direct-acting oral anticoagulants (DOACs) are commonly prescribed with antiseizure medications (ASMs) due to concurrency of and the association between atrial fibrillation (AF) and epilepsy. However, enzyme-inducing (EI) ASMs may reduce absorption and accelerate metabolism of DOACs, potentially lowering DOAC levels and elevating thromboembolism risk. Objective: To assess the rates of thromboembolic and major bleeding events in adults with AF and epilepsy dispensed DOACs and EI ASMs vs DOACs with non-EI ASMs. Design, Setting, and Participants: This active-comparator, new-user cohort study included US health care data from the Clinformatics Data Mart database from October 2010 to September 2021 for a nationally representative population of adults with AF and epilepsy. Exposure: Evaluations included episodes of contiguous coadministration of DOACs for AF with EI ASMs (exposed) or non-EI ASMs (referent) for epilepsy. Main Outcomes and Measures: Thromboembolic events (primary outcome) and major bleeding events (secondary outcome) were identified based on a series of validated, diagnosis-based coding algorithms. Data-adaptive, high-dimensional propensity score matching was used to control for observed confounders and proxies for unobserved confounders. Adjusted hazard ratios (AHRs) were estimated using Cox proportional hazards regression models with robust variance estimators to account for clustering within matched pairs. Results: This study included 14 078 episodes (median age, 74 [IQR, 67-81]; 52.4% female) and 14 158 episodes (median age, 74 [IQR, 67-81]; 52.4% female) of incident DOAC and ASM use that met eligibility criteria for assessment of thromboembolic and major bleeding outcomes, respectively. Incidence was 88.5 per 1000 person-years for thromboembolic events and 68.3 per 1000 person-years for bleeding events. Compared with use of non-EI ASMs, use of EI ASMs with DOACs was not associated with a difference in risk of thromboembolic events (AHR, 1.10; 95% CI, 0.82-1.46) but was associated with a reduction in risk of major bleeding events (AHR, 0.63; 95% CI, 0.44-0.89). Conclusions and Relevance: In this cohort study, EI ASMs were not associated with alteration in DOAC efficacy. Further research is needed on the reduction in bleeding risk associated with EI ASMs, as this may suggest that pharmacokinetic interactions are associated with lowering DOAC levels without negating therapeutic effects.

  PublisherDOI

Recent grants

• Impact of Anticholinergic and Dopamine Receptor Blocking Drug Exposure on Parkinson Disease Trajectory and Outcomes

  NIH · $2.9M · 2017–2023

• Neurologic Clinical Epidemiology Training Program

  NIH · $4.0M · 2008–2029

• Parkinson Disease Disparities and Outcomes

  NIH · $669k · 2012–2016

Frequent coauthors

• Dylan Thibault

  West Virginia University

  213 shared

• Nabila Dahodwala

  University of Pennsylvania

  107 shared

• Brad A. Racette

  Barrow Neurological Institute

  82 shared

• Michelle Fullard

  University of Colorado System

  82 shared

• Jason M. Schwalb

  70 shared

• Drew S. Kern

  70 shared

• Michelle A. Burack

  65 shared

• Lisa M. Shulman

  University of Maryland, Baltimore

  65 shared

Labs

• Allison Willis LabPI

Education

• M.D.

  University of Illinois College of Medicine

  2002

• Other

  Washington University School of Medicine

  2013

Awards & honors

• Faculty Scholar, Center for Clinical Epidemiology and Biosta…
• Faculty Scholar, Institute of Aging, University of Pennsylva…
• Senior Scholar, Leonard Davis Institute of Health Economics,…
• Faculty Scholar, Center for Real World Effectiveness and Saf…
• Co-Director, Resource Center for Minority Aging Research, Un…