{"doi":"10.1002/mds.70048","title":"Frozen in Addiction: A New Wave of Drug‐Induced Movement Disorders?","abstract":"Movement disorders resulting from illicit drug use can present with both hypokinetic and hyperkinetic features often leading to severe functional impairment. The seminal publication by Langston and colleagues,1 for example, described four adults who became parkinsonian within a week of being exposed to heroin contaminated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). These first cases marked the beginning of sporadic outbreaks of parkinsonism linked to synthetic opioid use.2 The cause was attributed to MPP+, a MAO-B metabolite of MPTP, which results in mitochondrial dysfunction and neuronal death.2 Importantly, although these cases affected relatively few individuals worldwide, they were pivotal in highlighting the vulnerability of dopamine-producing neurons to a variety of neurotoxins and established groundbreaking models for studying Parkinson's disease (PD).2 Other examples of drug-induced movement disorders include dystonia-parkinsonism resulting from manganese toxicity due to ephedrine (methcathinone) use3 and chorea and dystonia—also referred to as “crack-dancing”—or tics caused by cocaine use.4 Over the past few years, a new and much larger-scale trend of people with movement disorders caused by illicit drug use has emerged. This phenomenon appears to be driven by synthetic opioids such as fentanyl and its analogues, often combined with the veterinary sedative xylazine, the combination colloquially known as “tranq,” as well as methamphetamines.5-7 Although the epicenter is the United States and Canada, cases have been reported by prominent media outlets in various parts of the world.7-11 Affected individuals commonly exhibit characteristic postural and other motor abnormalities, which from a phenomenological standpoint have important similarities with movement disorders such as camptocormia in parkinsonism or generalized dystonia. This hypothesis-driven connection has not been sufficiently considered, despite its potential to deepen our knowledge about the mechanisms modulating postural motor control. Given the alarming prevalence of this phenomenon, it further holds significant implications for public health. Here, we draw from our own experience and use knowledge from neuroscience of motor control and movement disorders to speculate about the relationship between abnormal postural control and regular exposure to illicit fentanyl, xylazine, and methamphetamines, including combination use. We also highlight open questions that will need to be addressed in future research. A characteristic phenotype linked to the current drug-use epidemic reported in the media is people with markedly bent spines, often flexed forward and while standing.7-11 This distinctive posture that is primarily attributed to fentanyl drug use, and its various mixtures, including methamphetamines and xylazine,5, 6 has drawn worldwide attention (see Supporting Information Data S1). However, postural abnormalities linked to opioid use have been noted for some time, including forward head posture and thoracic “hyperkyphosis.”12 Slang terms such as “heroin hunch” or “fentanyl fold” are often used to describe the effects of high-potency synthetic opioids on the body, which are arguably most often acute and initially reversible. Notwithstanding, it is documented that some people may have persistent postural abnormalities (Fig. 1, Video S1), even in cases after cessation of drug use.13 At this point it is unclear why some individuals are at higher risk for permanent postural changes. In fact, this issue is so prevalent and disabling that physical rehabilitation to specifically address it is often part of comprehensive opioid recovery programs.14 From a phenomenology standpoint, the bent spines of people with daily illicit synthetic opioid use can look strikingly similar to camptocormia, as seen in parkinsonism. The latter describes the involuntary marked flexion of the thoracolumbar spine that appears during standing or walking and may resolve i","journal":"Movement Disorders","year":2025,"id":554382,"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":1,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9524,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1233111,"name":"Roberto Erro","orcid":"0000-0002-7800-7419","position":1,"is_corresponding":false},{"id":1451627,"name":"Mohammad Abdullah","orcid":"0000-0002-4650-7726","position":2,"is_corresponding":false},{"id":1451628,"name":"Tanya S. Hauck","orcid":"0000-0001-7407-3278","position":3,"is_corresponding":false},{"id":331971,"name":"Daniel Ciccarone","orcid":"0000-0002-2355-5477","position":4,"is_corresponding":false},{"id":342861,"name":"Christy Sutherland","orcid":"0000-0002-2069-4172","position":5,"is_corresponding":false},{"id":1451629,"name":"Parisa Saiyarsarai","orcid":"0000-0001-8015-1834","position":6,"is_corresponding":false},{"id":341997,"name":"Connie Marras","orcid":"0000-0002-9236-9328","position":7,"is_corresponding":false},{"id":245790,"name":"Susan H. Fox","orcid":"0009-0004-7568-1645","position":8,"is_corresponding":false},{"id":263851,"name":"Alfonso Fasano","orcid":"0000-0001-5346-0180","position":9,"is_corresponding":false},{"id":17424,"name":"Anthony E. Lang","orcid":"0000-0003-1229-3667","position":10,"is_corresponding":false},{"id":1452195,"name":"Jonathan Squires","orcid":null,"position":11,"is_corresponding":false},{"id":567334,"name":"Kailash P. Bhatia","orcid":"0000-0001-8185-286X","position":12,"is_corresponding":false},{"id":301276,"name":"Christos Ganos","orcid":"0000-0001-8077-8530","position":0,"is_corresponding":true}],"reference_count":47,"raw_metadata":null,"created_at":"2026-07-19T02:54:50.112989Z","pmid":"41103206","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":[]}