{"doi":"10.1002/mdc3.14305","title":"A Call for Change: Updating the Operational Definition for Dementia in Parkinson's Disease","abstract":"In Parkinson's disease (PD), cognitive dysfunction ranges from subjective cognitive complaints to mild cognitive impairment (PD-MCI) and PD dementia (PDD). Timely identification and management of cognitive impairment are major challenges in PD, with substantial burdens on those affected and healthcare systems.1 Recognizing the need for criteria for different stages of cognitive impairment in PD, the Movement Disorder Society (MDS) commissioned task forces developed clinical diagnostic criteria for PDD2 (2007) and PD-MCI3 (2012) to identify cognitive impairments and ensure uniform participant criteria for therapeutic trials. The criteria, based on literature review and expert consensus, provide recommendations for diagnostic procedures that operationalize PDD4 and PD-MCI3 diagnoses and allow for Level I and II assessments (depending on available time and resources), which have both undergone formal validation.5, 6 The PD-MCI criteria have not only advanced the field regarding clinical, biomarker, genetic features and the conversion to PDD, but also facilitated pathways for industry and regulatory authorities to conduct clinical trials, specifically addressing this “at risk” stage of cognitive impairment.7 At the time when the PDD criteria were established, however, there was still considerable influence from the Alzheimer's disease (AD) field and few robust biomarkers. Indeed, the only symptomatic medication approved by regulatory authorities for PDD (namely rivastigmine) used the ADAS-cog, as the primary outcome measure.8 Even recent PDD trials vary substantially in their inclusion criteria and outcome measures selected, making reliable comparisons among studies or conducting meta-analyses nearly impossible. Since the publication of the PDD criteria, considerable progress has been made in understanding the course and causes of cognitive deterioration in PD, along with the evolution of biofluid and imaging biomarkers.9 Clinically, this progress includes a greater appreciation of behavioral complications that often accompany cognitive progression, as well as the heterogeneity of PD cognitive phenotypes and differing trajectories. Technological advances now offer computerized, smartphone and online assessments, providing novel approaches for assessing neuropsychological and functional abilities.10 Subgroups at higher risk of progressing to PDD have been identified from genetic risk factors and associated clinical features, such as Rapid Eye Movement Sleep Behavior Disorder (RBD) and motor phenotype.11 It is now recognized that cognitive impairment can begin in the prodromal and early phases of PD with many patients satisfying diagnostic criteria for PD-MCI at the time of PD diagnosis. The recognition of prodromal cognitive impairment, prior to or after motor symptom onset, has blurred the diagnostic boundaries between PD12 and dementia with Lewy bodies (DLB),13-15 with added challenges of defining prodromal PD16 and prodromal DLB,17 and PD-MCI and DLB-MCI.18 Whether these observations and the emergence of diagnostic biomarkers of alpha-synuclein (eg, alpha-synuclein seed amplification assay [a-syn SAA]), dopaminergic neuron dysfunction, or neurodegeneration as proposed in recent biological frameworks will unify PD and DLB as a single diagnostic entity remains to be seen, but these distinctions further highlight the need to go beyond our existing diagnostic framework that was developed more than 15 years ago. Considerable progress has been made in developing neurodegenerative biomarkers (eg, in vivo assays with biofluids, tissues, imaging) that reflect putative underlying pathobiology. Utilization of accurate biomarkers that allow for disease-modifying therapies to be introduced at the earliest time point is a desired strategy, and the development of a biological diagnosis for AD based on amyloid, tau, and neurodegeneration biomarkers now allows for such treatments to enter clinical practice.19 Recent development of a-syn SAAs off","journal":"Movement Disorders Clinical Practice","year":2024,"id":429312,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":10,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9607,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2024-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":230246,"name":"Irene Litvan","orcid":"0000-0002-3485-3445","position":1,"is_corresponding":false},{"id":80309,"name":"Daniel Weintraub","orcid":"0000-0003-0633-7168","position":2,"is_corresponding":false},{"id":108600,"name":"Jennifer G. Goldman","orcid":"0000-0001-5014-7535","position":3,"is_corresponding":false},{"id":250775,"name":"Alexander I. Tröster","orcid":"0000-0002-8898-3878","position":4,"is_corresponding":false},{"id":108605,"name":"Simon J.G. Lewis","orcid":"0000-0002-4093-7071","position":5,"is_corresponding":false},{"id":1231951,"name":"International Parkinson and Movement Disorder Society PD‐MCI Study Group","orcid":null,"position":6,"is_corresponding":false},{"id":92190,"name":"Jaime Kulisevsky","orcid":"0000-0003-4870-1431","position":0,"is_corresponding":true}],"reference_count":40,"raw_metadata":null,"created_at":"2026-07-19T01:59:06.668462Z","pmid":"39688346","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}