Diagnostic accuracy of the 'Dysphagia Screening Tool for Geriatric Patients' (DSTG) compared to Flexible Endoscopic Evaluation of Swallowing (FEES) for assessing dysphagia in hospitalized geriatric patients - a diagnostic study.

BACKGROUND: Oropharyngeal dysphagia is highly prevalent among hospitalized geriatric patients. The screening instruments used to date have been evaluated primarily in stroke patients. This diagnostic study aimed to validate a new screening instrument for oropharyngeal dysphagia, the 'Dysphagia Screening Tool for Geriatric Patients' (DSTG), as compared to one of the gold standards, flexible endoscopic evaluation of swallowing (FEES). MATERIALS AND METHODS: Geriatric inpatients admitted to five geriatric hospitals in Germany were consecutively evaluated using both DSTG and FEES in random order and by different evaluators blinded to the results of the other evaluation. In the FEES examination, a score of more than 3 on Rosenbek's Penetration Aspiration Scale was considered evidence of clinically relevant oropharyngeal dysphagia. Sensitivity, specificity and further measures of test performance were calculated for DSTG. RESULTS: The 53 volunteers recruited were on average 85 years of age, 56.6% were women. Twenty patients (37.7%) were diagnosed with dysphagia using FEES. Of these, 12 were screened as positive on DSTG. Of the 33 FEES negative patients, 4 tested positive on DSTG. The following test parameters were calculated for DSTG: sensitivity: 0.60, 95% confidence interval [0.39 ; 0.78], specificity 0.88 [0.73 ; 0.95], positive predictive value 0.75 [0.51 ; 0.90], negative predictive value 0.78 [0.63 ; 0.89], positive likelihood ratio 4.95 [1.85 ; 13.27], negative likelihood ratio 0.46 [0.26 ; 0.79]. In a receiver-operator characteristic (ROC) curve analysis, the area under the curve (AUC) was 0.77 [0.62 ; 0.91]. No adverse events occurred. CONCLUSION: The DSTG appears to be a valid instrument for screening of oropharyngeal dysphagia in geriatric inpatients.

Characterization of patients admitted to specialized geriatric acute care hospital units with the German version of the Standardized Evaluation and Intervention for Seniors at Risk (SEISAR) screening-instrument: a cross-sectional study.

BACKGROUND: The Standardized Evaluation and Intervention for Seniors at Risk (SEISAR) screening tool records major geriatric problems, originally applied in the emergency department. Particularly, the distinction of compensated and uncompensated problems is an interesting and new approach. Therefore, we translated the SEISAR in German language and used it to characterize patients in specialized geriatric hospital wards in Germany and to gather initial experience regarding its usability and practicability. METHODS: The tool was translated by three independent specialists in geriatric medicine and backtranslated for quality-assurance by a non-medical English native speaker. In a second step, 8 acute care geriatric hospital departments used the translated version to characterize all consecutive patients admitted over a period of one month between December 2019 and May 2020 at time of admission. RESULTS: Most of the 756 patients (78%) lived in an own apartment or house prior to hospital admission. Participants had on average 4 compensated and 6 uncompensated problems, a Barthel-Index of 40 pts. on admission with a median increase of 15 points during hospital stay, and a median length of stay of 16 days in the geriatric hospital department. CONCLUSION: SEISAR is an interesting standardized brief comprehensive geriatric assessment tool for the identification of compensated and uncompensated health problems in older persons. The data of this study highlights the number, variability, and complexity of geriatric problems in patients treated in specialized acute care geriatric hospital wards in Germany. TRIAL REGISTRATION: German Clinical trial register (DRKS-ID: DRKS00031354 on 27.02.2023).

Acute disease induced cognitive dysfunction in older patients - an unrecognized syndrome.

BACKGROUND: It is unknown, how many older hospitalized patients experience cognitive changes independently from delirium. METHODS: In this retrospective study, cognitive function was assessed with the Montreal Cognitive Assessment on admission and discharge in 103 acute care geriatric hospital patients. RESULTS: Mean age was 80.8 ± 7.3 years. The total MoCA score on admission was 17.8 (±4.5) and at discharge 17.7 (±4.4). The mean difference of the total MoCA score was - 0.1 (±3.5). 12 (11.7%) patients suffered from delirium. 46 (44.7%) patients experienced significant changes of cognitive function <- 2 or > 2 MoCA points without delirium. There was no significant association between delirium during hospital stay and the prevalence and magnitude of changes in total MoCA score. CONCLUSION: Cognitive changes frequently occur during acute disease of geriatric patients independently from delirium. We propose the term "acute disease induced cognitive dysfunction" (ADICD) for this entity. TRIAL REGISTRATION: German Clinical trial register (DRKS-ID: DRKS00025157 on 28.04.2021).

[Dysphagia - from Pathophysiology to Treatment]. / Dysphagie ­ von der Pathophysiologie zur Therapie.

More than 5 million persons in Germany suffer from swallowing disorders (dysphagia), predominantly oropharyngeal dysphagia. Due to the demographic changes in our population, the prevalence rates are expected to increase. Multiple conditions may be the cause of dysphagia and dysphagia may lead to various symptoms. Esophageal dysphagia is predominantly accompanied by regurgitation, vomiting, pain and foreign body sensation in the esophageal region. Oropharyngeal dysphagia is characterized by cough, hawking and airway disease. In some patients with oropharyngeal dysphagia, symptoms may be completely absent or are not attributed to dysphagia. Both forms of dysphagia are regularly accompanied by difficulties with nutritional intake and consecutive malnutrition. Therefore, the diagnostic and therapy of dysphagia should always be accompanied by nutritional support.

Inflammatory cytokines and appetite in older hospitalized patients.

It has already been confirmed that the decline in appetite during disease is a common issue and the biologic players of inflammation such as cytokines may serve as mediators of this effect. This study aimed to investigate the association of appetite with individual cytokines that could be involved in the inflammation-associated loss of appetite in acutely ill older hospitalized patients. 191 patients (mean age 81.3 ± 6.6 years, 64% women) participated in this prospective observational study. Risk of malnutrition and patient's appetite were evaluated using the Mini Nutritional Assessment Short Form and the Simplified Nutritional Appetite Questionnaire on admission, respectively. Serum C-reactive protein (CRP) and serum cytokines such as Interleukin 1 beta (IL-1ß), IL-6, IL-8, IL-10, IL-12p70, IL-17, IL-18, IL-23 and IL-33, interferon alpha-2, interferon gamma, tumor necrosis factor alpha and monocyte chemoattractant protein-1 (MCP-1) were measured. Of total population, 30% had CRP>3.0 (mg/dL), 31% were malnourished and 31% demonstrated poor and very poor appetite. There were significant differences in the mean concentrations of a number of cytokines including IL-1ß, MCP-1, IL-6, IL-10, IL-12p70, IL-18 and IL-23 across the appetite scores. In a regression analysis, an increased IL-18 level (P = 0.049) was the most prominent biomarker for poor appetite. No other significant associations between appetite and circulating levels of other cytokines were found in the regression analysis, except for IL-6 and IL-33, which were only significantly associated in the unadjusted model. The association of IL-18 with decreased appetite was independent from the severity of CRP-level and infections. In this study, certain cytokines, in particular IL-18 were associated with poor appetite in acutely diseased patients and should therefore be considered as a potential target of the prevention and treatment of malnutrition.

[How the brain perceives the world in old age with all senses]. / Wie das Gehirn die Welt im Alter mit allen Sinnen wahrnimmt.

BACKGROUND: Aging is a multidimensional process that may lead to physical, psychological and social changes. This is predominantly due to a decline of sensory functions and their central processing. MATERIAL AND METHODS: Selective literature search in Medline and the Cochrane Library. RESULTS: In addition to specific disorders of the sensory organs, unspecific age-related degenerative processes are responsible for the high prevalence of sensory limitations in older people. This can lead to a significant reduction in the quality of life. Balance impairment, decreasing function of hearing, vision, smell and the somatosensory system are associated with an increased risk of falling and an increased mortality in older people. Furthermore, there is evidence for a link between hearing loss and cognitive decline. In addition to the functional ability of every sense on its own, the integration of multiple sensory perceptions plays an increasing role in age-related sensory limitations. CONCLUSION: Sensory impairments have to be considered when working with older people. Early detection and an interdisciplinary therapeutic approach can reduce the negative consequences. Multimodal stimulation appears to stimulate brain plasticity which helps to compensate age-related changes.

The impact of acute changes of inflammation on appetite and food intake among older hospitalised patients.

The present study aimed to investigate the effect of acute changes in serum C-reactive protein (CRP) on appetite and food intake among older hospitalised patients. A total of 200 patients (age range 65-94 years, 62·5 % women) participated in this prospective longitudinal observational study. Risk of malnutrition was measured according to the Mini Nutritional Assessment Short Form. The Simplified Nutritional Appetite Questionnaire (SNAQ) and Edmonton Symptom Assessment System (ESAS) were used to evaluate patients' appetite at the time of hospital admission (baseline) and after 7 d (follow-up). Food intake was measured according to the plate diagram and serum CRP was analysed at baseline and follow-up. At baseline, 30·5 % of the patients had moderate to severe inflammation, 31·0 % were malnourished and 48·0 % had food intake <75 % of the meals offered. Also, 32·5 and 23·5 % reported poor and very poor appetite or severe loss of appetite according to the SNAQ and ESAS, respectively. Of the patients, 40 % displayed a pronounced reduction in median CRP levels by -1·2 mg/dl and 19 % demonstrated an increase in median CRP levels by +1·2 mg/dl. Appetite significantly improved (P = 0·006) in patients with a decrease in CRP level and deteriorated in those with an increase in CRP level (P = 0·032). Changes in CRP levels did not show any significant impact on food intake. In a regression analysis, changes of inflammation were the major independent predictor for changes of patients' appetite. We conclude that inflammation has a significant impact on appetite and should therefore be considered in the diagnosis and treatment of malnutrition.

The impact of disease-related immobilization on thigh muscle mass and strength in older hospitalized patients.

BACKGROUND: We assessed the quantitative changes in muscle mass and strength during 2 weeks of hospitalization in immobile and mobile acutely ill hospitalized older adults. METHODS: Forty-one patients (82.4 ± 6.6 years, 73.0% females) participated in this prospective longitudinal observational study. Mobility status was defined according to walking ability as described in the Barthel-Index. Functional status, including handgrip strength and isometric knee-extension strength, and mid-thigh magnetic resonance imaging (MRI) measurements of cross-sectional area (CSA) were conducted on admission and at discharge. RESULTS: Twenty-two participants (54%) were immobile and 19 (46%) mobile. In all, 54.0 and 12.0% were at risk of malnutrition and malnourished, respectively. The median time between baseline and follow-up for MRI scans were 13 days in mobile and immobile participants (P = 0.072). Mid-thigh muscle and subcutaneous fat CSA significantly decreased by 3.9cm2 (5.0%, P = 0.002) and 5.3cm2 (5.7%, P = 0.036) during hospitalization whereas intermuscular fat remained unchanged in immobile subjects. No significant changes were observed in mobile patients. In a regression analysis, mobility was the major independent risk factor for changes in mid-thigh muscle CSA as a percentage of initial muscle area (P = 0.022) whereas other variables such as age (P = 0.584), BMI (P = 0.879), nutritional status (P = 0.835) and inflammation (P = 0.291) were not associated with muscle mass changes. There was a significant decrease in isometric knee extension strength (P = 0.002) and no change in handgrip strength (P = 0.167) in immobile patients whereas both parameters increased significantly over time in mobile patients (P = 0.048 and P = 0.012, respectively). CONCLUSIONS: Two weeks of disease-related immobilization result in a significant loss of thigh muscle mass and muscle strength in older patients with impaired mobility. Concomitantly, there was a significant reduction of subcutaneous adipose tissue in immobile older hospitalized patients whereas no changes were observed in intermuscular fat among these patients. These data highlight the importance of mobility support in maintaining muscle mass and function in older hospitalized patients.

Neurogeriatrics-a vision for improved care and research for geriatric patients with predominating neurological disabilities.

Geriatric medicine is a rapidly evolving field that addresses diagnostic, therapeutic and care aspects of older adults. Some disabilities and disorders affecting cognition (e.g. dementia), motor function (e.g. stroke, Parkinson's disease, neuropathies), mood (e.g. depression), behavior (e.g. delirium) and chronic pain disorders are particularly frequent in old subjects. As knowledge about these age-associated conditions and disabilities is steadily increasing, the integral implementation of neurogeriatric knowledge in geriatric medicine and specific neurogeriatric research is essential to develop the field. This article discusses how neurological know-how could be integrated in academic geriatric medicine to improve care of neurogeriatric patients, to foster neurogeriatric research and training concepts and to provide innovative care concepts for geriatric patients with predominant neurological conditions and disabilities.

Dysphagia and pharmacotherapy in older adults.

PURPOSE OF REVIEW: The review summarizes current knowledge and recent findings about how to practically apply medication in patients with dysphagia and how swallowing function may be positively or negatively affected by drugs. RECENT FINDINGS: Oropharyngeal dysphagia is a major health problem in older persons and was recently classified as a geriatric syndrome. Although the knowledge about an effective diagnostic approach increased during the last years, comparatively little is known about how to effectively manage and treat dysphagia and hardly anything is implemented in clinical routine. Studies have shown a considerable lack of knowledge about the adequate modification of medication and demonstrated an increased rate of practical medication errors in patients with dysphagia. With regard to dysphagia therapy, two systematic reviews have identified neuroleptics as potentially harmful for swallowing function. The role of other candidates is controversial. Contrary to this, some pharmacological approaches may be future options for the treatment of dysphagia, with capsaicin currently being the most evaluated and potential one. SUMMARY: More professional training and advice about the adequate management of medication in dysphagic patients is necessary for all healthcare professionals. Large observational and interventional studies are needed to identify and confirm the influence of pharmacological substances on the swallowing function.

Blood Thiamine Level and Cognitive Function in Older Hospitalized Patients.

AIM: We sought to identify any association between whole blood thiamine level and functional status in older hospitalized patients. METHODS: This cross-sectional study retrospectively analyzed the results of routine measurements of whole blood thiamine levels of 233 older patients who were consecutively hospitalized to a geriatric acute care ward. Nutritional status, depression, and the participants' cognitive impairment were evaluated using the Mini Nutritional Assessment-Short Form, Depression in Old Age Scale, and Montreal Cognitive Assessment, respectively. Activities of daily living were determined using Barthel Index (BI) on admission and at the time of discharge. Diagnoses of dementia and delirium were derived from the patients' medical records. RESULTS: Of 233 participants (mean age 82.1 [7.1]), 47.0% and 39.0% were at risk of malnutrition and malnourished, respectively. There was no thiamine deficiency (<20 ng/mL) in total population. Nearly all patients (95%) were screened with impaired cognitive function, in which 36% and 9% had the diagnosis of dementia and delirium, respectively. Patients with dementia (P = .040) and delirium (P = .002) demonstrated lower mean thiamine blood levels compared to patients without. Mean blood vitamin B1 was higher in patients with functional recovery (change in BI ≥5 points during hospitalization; P = .018). In a binary logistic regression analysis, blood vitamin B1, weight loss, and female gender were the major independent risk factors for delirium but not for dementia. CONCLUSION: Despite the absence of thiamine deficiency, whole blood thiamine was lower in patients with dementia and delirium compared to those without. Higher thiamine levels were significantly associated with functional recovery during hospitalization.

Impact of sarcopenia on 1-year mortality in older patients with cancer.

OBJECTIVES: sarcopenia is common especially in hospitalised older populations. The aim of this study was to assess the prevalence of sarcopenia, defined as low skeletal mass and muscle strength, and its impact on 1-year mortality in older patients with cancer. METHODS: skeletal muscle mass was estimated using bioelectric impedance analysis and related to height2 (SMI; Janssen et al. 2002). Grip strength was measured with the JAMAR dynamometer and the cut-offs suggested by the European Working Group on Sarcopenia in Older People (EWGSOP) were applied. One-year mortality was assessed by telephone follow-up and the local cancer death registry. RESULTS: of the 439 consecutively recruited cancer patients (60-95 years; 43.5% women), 119 (27.1%) had sarcopenia. Of the patients with sarcopenia, 62 (52.5%) died within 1 year after study entry compared to 108 (35.1%) patients who did not have sarcopenia (P = 0.001). In a stepwise, forward Cox proportional hazards analysis, sarcopenia (HR = 1.53; 95% CI: 1.034-2.250; P < 0.05), advanced disease (HR = 1.87; 95% CI: 1.228-2.847; P < 0.05), number of drugs/day (HR = 1.11; 95% CI: 1.057-1.170; P < 0.001), tumour diagnosis (overall P < 0.05) and Karnofsky index (HR = 0.98, 95% CI: 0.963-0.995; P < 0.05) associated with 1-year mortality risk. The factors sex, age, co-morbidities and involuntary 6-month weight loss ≥5% were insignificant. CONCLUSIONS: sarcopenia was present in 27.1% of older patients with cancer and was independently associated with 1-year mortality. The fact that sarcopenia was nearly as predictive for 1-year mortality as an advanced disease stage underlines the importance of preservation of muscle mass and function as a potential target of intervention in older patients with cancer.

Dysphagia from a neurogeriatric point of view : Pathogenesis, diagnosis and management.

Dysphagia is becoming increasingly more common in aging societies and, like the classical geriatric syndromes, it is a relevant functional impairment. The prevalence of dysphagia is highest in the group of old patients with neurological disorders, particularly in patients with stroke, dementia and Parkinson's disease. In the various neurological diseases of older people disease-specific factors often have a decisive influence on the clinical management of dysphagia. In addition, the concept of primary and secondary presbyphagia plays an important role in understanding age-related dysphagia. Whereas at the organ level of the International Classification of Functioning, Disability and Health (ICF) model, the diagnosis and treatment of dysphagia in neurogeriatrics have already made progress, more research is needed on the levels of activity/mobility, social environment, personal factors and the environment. This article summarizes the pathophysiological aspects as well as the current evidence for diagnosis and treatment of neurogeriatric dysphagia. Due to its high clinical relevance dysphagia should be added to the geriatric syndromes as "impaired swallowing".

[Geriatric intensive care : Consensus paper of DGIIN, DIVI, DGAI, DGGG, ÖGGG, ÖGIAIN, DGP, DGEM, DGD, DGNI, DGIM, DGKliPha and DGG]. / Geriatrische Intensivmedizin : Konsensuspapier der DGIIN, DIVI, DGAI, DGGG, ÖGGG, ÖGIAIN, DGP, DGEM, DGD, DGNI, DGIM, DGKliPha und DGG.

The proportion of elderly, frail, and multimorbid people has increased dramatically in recent decades resulting from demographic changes and will further increase, which will impact acute medical care. Prospective, randomized studies on geriatric intensive care are still lacking. There are also no international or national recommendations regarding the management of critically ill elderly patients. Based on an expert opinion, this consensus paper provides 16 statements that should be considered when dealing with geriatric critical care patients.

Secondary Metabolites from Escovopsis weberi and Their Role in Attacking the Garden Fungus of Leaf-Cutting Ants.

The specialized, fungal pathogen Escovopsis weberi threatens the mutualistic symbiosis between leaf-cutting ants and their garden fungus (Leucoagaricus gongylophorus). Because E. weberi can overwhelm L. gongylophorus without direct contact, it was suspected to secrete toxins. Using NMR and mass spectrometry, we identified several secondary metabolites produced by E. weberi. E. weberi produces five shearinine-type indole triterpenoids including two novel derivatives, shearinine L and shearinine M, as well as the polyketides, emodin and cycloarthropsone. Cycloarthropsone and emodin strongly inhibited the growth of the garden fungus L. gongylophorous at 0.8 and 0.7 µmol, respectively. Emodin was also active against Streptomyces microbial symbionts (0.3 µmol) of leaf-cutting ants. Shearinine L instead did not affect the growth of L. gongylophorus in agar diffusion assays. However, in dual choice behavioral assays Acromyrmex octospinosus ants clearly avoided substrate treated with shearinine L for the garden fungus after a 2 d learning period, indicating that the ants quickly learn to avoid shearinine L.

Prevalence and predictors of vitamin D-deficiency in frail older hospitalized patients.

BACKGROUND: Vitamin D deficiency is known to be highly prevalent in older persons. However, the prevalence in the subgroup of frail older hospitalized patients is not clear. We sought to investigate the prevalence and predictors of vitamin D deficiency in frail older hospitalized patients. METHODS: 217 consecutively geriatric hospitalized patients with routine measurements of 25-hydroxyvitamin D [25 (OH)D] at hospital admission were analyzed retrospectively, including information of previous vitamin D supplementation and the geriatric assessment. Serum 25 (OH)D concentrations < 20 ng/ml and between 20 and 29.99 ng/ml were classified as deficient and insufficient, respectively, whereas concentrations ≥30 ng/ml were considered as desirable. A stepwise binary logistic regression model was performed to assess the simultaneous effects of age, gender and geriatric assessments on the prevalence of low vitamin D concentration. RESULTS: Mean age of the cohort was 81.6 ± 8.0 years (70.0% females). Mean serum 25(OH)D was 12.7 ± 12.9 ng/ml. Of 167 (77%) subjects without known previous vitamin D supplementation, only 21 (12.6%) had serum concentrations ≥20 ng/ml and only 8 (4.2%) had desirable serum concentrations ≥30 ng/ml. In total population, 146 (87.4%) participants were vitamin D deficient. Despite vitamin D supplementation, 22 of 50 participants (44.0%) were vitamin D deficient and only 19 (38.0%) had desirable concentrations of ≥30 ng/ml. In a stepwise logistic regression analysis, only previous intake of vitamin D supplementation and high Geriatric Depression Scale score (GDS-15) were significantly associated with vitamin D deficiency. CONCLUSIONS: In the group of frail older hospitalized patients without previous vitamin D supplementation, the prevalence of inadequate vitamin D concentrations is extremely high. Therefore, usefulness of the routine measurement of vitamin D status before initiating of supplementation appears to be questionable in this patient group.

[Percutaneous endoscopic gastrostomy in geriatrics : Indications, technique and complications]. / Die perkutane endoskopische Gastrostomie in der Altersmedizin : Indikationen, Technik und Komplikationen.

The technique of percutaneous endoscopic gastrostomy (PEG) was introduced in 1979 as a semi-invasive approach for children with the need for a gastric fistula in order to avoid an operative intervention. The suture pull-through method was rapidly established and is now omnipresent. Because scientific evidence is broadly missing, there is some uncertainty about the indications in geriatric medicine. Guidelines do not recommend the insertion of a PEG in patients with severe dementia and malnutrition. Tube feeding is mainly recommended as a temporary method for patients who cannot take oral nutrition for more than 3 days or for whom the energy intake for more than 10 days presumably covers less than 50% of their needs, assuming that the overall prognosis is reasonable. Insertion of a PEG is only recommended if artificial nutrition is expected to be necessary for more than 3-4 weeks or if a nasogastric tube is not tolerated.

[Refeeding syndrome in geriatric patients : A frequently overlooked complication]. / Refeeding-Syndrom bei geriatrischen Patienten : Eine oft übersehene Komplikation.

The refeeding syndrome is a life-threatening complication that can occur after initiation of a nutrition therapy in malnourished patients. If the risk factors and pathophysiology are known, the refeeding syndrome can effectively be prevented and treated, if recognized early. A slow increase of food intake and the close monitoring of serum electrolyte levels play an important role. Because the refeeding syndrome is not well known and the symptoms may vary extremely, this complication is poorly recognized, especially against the background of geriatric multimorbidity. This overview is intended to increase the awareness of the refeeding syndrome in the risk group of geriatric patients.

Biogeography of mutualistic fungi cultivated by leafcutter ants.

Leafcutter ants propagate co-evolving fungi for food. The nearly 50 species of leafcutter ants (Atta, Acromyrmex) range from Argentina to the United States, with the greatest species diversity in southern South America. We elucidate the biogeography of fungi cultivated by leafcutter ants using DNA sequence and microsatellite-marker analyses of 474 cultivars collected across the leafcutter range. Fungal cultivars belong to two clades (Clade-A and Clade-B). The dominant and widespread Clade-A cultivars form three genotype clusters, with their relative prevalence corresponding to southern South America, northern South America, Central and North America. Admixture between Clade-A populations supports genetic exchange within a single species, Leucocoprinus gongylophorus. Some leafcutter species that cut grass as fungicultural substrate are specialized to cultivate Clade-B fungi, whereas leafcutters preferring dicot plants appear specialized on Clade-A fungi. Cultivar sharing between sympatric leafcutter species occurs frequently such that cultivars of Atta are not distinct from those of Acromyrmex. Leafcutters specialized on Clade-B fungi occur only in South America. Diversity of Clade-A fungi is greatest in South America, but minimal in Central and North America. Maximum cultivar diversity in South America is predicted by the Kusnezov-Fowler hypothesis that leafcutter ants originated in subtropical South America and only dicot-specialized leafcutter ants migrated out of South America, but the cultivar diversity becomes also compatible with a recently proposed hypothesis of a Central American origin by postulating that leafcutter ants acquired novel cultivars many times from other nonleafcutter fungus-growing ants during their migrations from Central America across South America. We evaluate these biogeographic hypotheses in the light of estimated dates for the origins of leafcutter ants and their cultivars.