Memorial Delirium Assessment Scale (MDAS)

1. Abstract

The Memorial Delirium Assessment Scale (MDAS) is an internationally recognized, clinician-administered psychometric instrument specifically designed to quantify the severity of acute cognitive, neurobehavioral, and neuropsychiatric symptoms characteristic of delirium. Originally conceptualized and validated by William Breitbart and colleagues (1997) at Memorial Sloan Kettering Cancer Center, the MDAS was engineered to overcome the clinical and psychometric constraints of binary screening tools and lengthy diagnostic inventories. Delirium represents an acute, fluctuating organic brain syndrome marked by disturbances in attention, arousal, cognition, and perception, bearing high morbidity and mortality in hospitalized patients, particularly within palliative oncology, intensive care, and geriatric medicine. The MDAS consists of 10 items, each rated on a 4-point ordinal Likert-type severity scale ranging from 0 (none / normal) to 3 (severe), yielding a potential aggregate score from 0 to 30. The scale captures four critical symptomatic domains: cognitive failure and attention deficits (reduced level of consciousness, disorientation, short-term memory impairment, impaired digit span, and reduced ability to maintain and shift attention), thought organization (disorganized thinking), neuropsychiatric phenomena (perceptual disturbances and delusions), and behavioral/neurovegetative dysregulation (decreased or increased psychomotor activity and sleep-wake cycle disturbance).

Extensive psychometric investigations have established that the MDAS exhibits robust internal consistency, with Cronbach’s alpha coefficients consistently spanning between .77 and .92 across diverse acute care, intensive care, and palliative settings. Test-retest reliability ranges from .75 to .85, while inter-rater reliability among trained clinicians, psychiatrists, and palliative care specialists frequently surpasses intraclass correlation coefficients (ICC) of .90. Construct validity is supported by strong convergent associations with established diagnostic criteria (e.g., DSM-III-R, DSM-IV, and DSM-5) and parallel assessment metrics, including the Delirium Rating Scale-Revised-98 (DRS-R-98) and the Confusion Assessment Method (CAM). Furthermore, clinical cutoff scores of 13 or greater yield optimal sensitivity (70.6% to 80%) and specificity (93.8% to 95%) for diagnostic confirmation in palliative samples, while lower thresholds (such as 7 to 10) provide heightened sensitivity in general geriatric and post-operative environments. Its rapid administration time of approximately 10 to 15 minutes, high responsiveness to pharmacological and non-pharmacological clinical resolution, and robust factor structure make the MDAS a gold-standard instrument for bedside longitudinal monitoring and clinical trial endpoints in neurocognitive research.

2. Keywords

Memorial Delirium Assessment Scale, MDAS, delirium severity, acute encephalopathy, cognitive impairment, psycho-oncology, palliative care, psychometrics, neuropsychiatric assessment, rating scale

3. Authors

The Memorial Delirium Assessment Scale was developed by William Breitbart, M.D., along with multidisciplinary clinical researchers in the Department of Psychiatry and Behavioral Sciences at Memorial Sloan Kettering Cancer Center (MSKCC) in New York, NY, USA. Key co-investigators contributing to its initial development, cross-validation, and psychometric operationalization include Barry Rosenfeld, Ph.D., Mark J. Roth, M.D., Finny T. Smith, M.A., Kimberly Cohen, M.D., Shuster J.L., M.D., and M.J. Passik, Ph.D. Subsequent methodological and comparative analyses have frequently evaluated the scale alongside tools developed by leading neuropsychiatric delirium scholars, notably Paula T. Trzepacz, M.D. (developer of the Delirium Rating Scale).

Author Institutional Affiliation:
Department of Psychiatry and Behavioral Sciences
Memorial Sloan Kettering Cancer Center
1275 York Avenue, New York, NY 10065, USA.
Correspondence regarding the original development has historically been addressed to William Breitbart, M.D., Chairman Emeritus of the Department of Psychiatry and Behavioral Sciences, MSKCC.

4. Purpose

Delirium is an acute, fluctuating neuropsychiatric syndrome characterized by concurrent disruptions in consciousness, attention, cognitive processing, circadian rhythms, and psychomotor dynamics. In tertiary care hospitals, intensive care units (ICUs), and oncology inpatient units, delirium incidence reaches 20% to 85%, significantly escalating the risk of inpatient mortality, protracted mechanical ventilation, prolonged hospitalization, permanent cognitive decline resembling dementia, and institutionalization. Historically, clinical assessment of delirium was impeded by a dichotomy: instruments were either dichotomous screening checklists—such as the Confusion Assessment Method (CAM)—that indicated the presence or absence of delirium without measuring its magnitude, or comprehensive, research-heavy instruments—such as the original Delirium Rating Scale (DRS)—which required extensive historical collateral information and substantial training, rendering them cumbersome for repeated daily administration at the bedside.

The primary purpose of the Memorial Delirium Assessment Scale is to provide a rapid, objective, clinically feasible, and psychometrically rigorous instrument capable of measuring the severity of delirium symptoms over time. Specifically, the MDAS was engineered to:

• Quantify Gradations of Symptom Severity: Rather than classifying a patient merely as “delirious” or “non-delirious,” the MDAS provides a continuous scalar score from 0 to 30. This permits clinicians to differentiate between mild subsyndromal states, moderate neurocognitive dysfunction, and severe acute encephalopathy.
• Monitor Longitudinal Clinical Trajectories: Due to its brief administration window (typically 10 to 15 minutes) and reliance on immediate interactive bedside tasks (such as digit span, word recall, and spatial-temporal orientation) supplemented by recent nursing or observer observations, the MDAS can be administered serially (e.g., twice daily or once every shift). This allows teams to track the resolution, worsening, or phenotypic fluctuation of the syndrome.
• Serve as an Evaluative Endpoint in Pharmacological and Interventional Trials: In clinical trials evaluating antipsychotics (e.g., haloperidol, olanzapine, quetiapine), alpha-2 adrenergic agonists (e.g., dexmedetomidine), or multi-component non-pharmacological interventions (e.g., the Hospital Elder Life Program [HELP]), the MDAS provides a reliable continuous dependent variable capable of detecting subtle treatment responses and therapeutic effect sizes.
• Assist in Clinical Diagnosis: Although fundamentally a severity metric, specific validated score thresholds permit the MDAS to operate as a sensitive diagnostic corroboration tool in complex populations, such as advanced cancer patients receiving high-dose opioids, palliative care inpatients, and post-operative geriatric surgical patients where baseline cognitive deficits and hypoactive presentations often obscure delirium detection.

5. Psychological Construct

Delirium represents an organic brain state characterized by widespread neurochemical, metabolic, and electrophysiological dysregulation across cortical and subcortical neural networks. The construct assessed by the MDAS is multidimensional, encapsulating four core syndromic domains that encompass the phenomenological manifestations outlined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R, DSM-IV, and DSM-5). The scale evaluates this construct through 10 distinct, operationalized target areas:

1. Level of Arousal and Consciousness

Delirium fundamentally disrupts the ascending reticular activating system (ARAS) and its projections to the thalamus and prefrontal cortex. Item 1 of the MDAS captures this basic substrate by rating the patient’s baseline alertness, awareness of external environmental cues, and spontaneous responsiveness to interpersonal interaction. Impairments manifest along a spectrum from normal environmental engagement to lethargy, obtundation, or hypervigilance wherein the patient cannot spontaneously apprehend their surroundings.

2. Cognitive and Attentional Processing

Attention is the psychometric backbone of delirium diagnosis. The MDAS operationalizes attention and cognitive processing across four discrete sub-items:

• Orientation (Item 2): Evaluates spatial, temporal, situational, and personal reference frameworks through a standardized 10-point query (date, month, day, year, season, floor, hospital name, city, state, country). Disorientation reflects failure of cortical integration, working memory consolidation, and continuous sensory updating.
• Short-Term Memory Impairment (Item 3): Assessed via immediate registration and subsequent 5-minute delayed recall of a 3-word standardized sequence. This probes hippocampal and parahippocampal integrity under conditions of transient interference.
• Impaired Digit Span (Item 4): Probes auditory working memory, executive attentional control, and central executive capacity via forward and backward repetition of digit sequences (up to 5 digits forward and 4 digits backward). Working memory failure directly indicates dorsolateral prefrontal cortex vulnerability.
• Reduced Ability to Maintain and Shift Attention (Item 5): Examines selective, sustained, and divided attention during conversational interaction. Clinicians observe whether the patient requires continual verbal prompting, exhibits distractibility from extraneous background noises, or demonstrates cognitive perseveration and wander.

3. Organization of Thought Processes

Item 6 evaluates Disorganized Thinking, a hallmark of acute cognitive fragmentation. This construct reflects executive dysfunction, disrupted language processing, and semantic incoherence. Patients demonstrate circumstantiality, tangentiality, loose associations, rambling speech, or completely unintelligible responses when prompted with open-ended, complex clinical questions (e.g., “Describe your current medical condition”).

4. Perceptual and Neuropsychiatric Phenomena

Psychotic manifestations in delirium emerge from cortical misprocessing and aberrant sensory gating:

• Perceptual Disturbances (Item 7): Measures sensory distortions, visual or auditory illusions (misinterpreting shadows, medical equipment, or IV tubing), and frank hallucinations (most commonly visual, though auditory, tactile, or somatic phenomena can occur).
• Delusions (Item 8): Captures persecutory ideation, paranoid misinterpretations, or systematized false, fixed beliefs (e.g., convictions that nursing staff are impostors, poisoners, or captors). Delusional states often trigger significant existential distress and behavioral agitation.

5. Psychomotor and Neurovegetative Regulation

The motor and chronobiological domains reflect disruptions in basal ganglia circuitry, brainstem nuclei, and suprachiasmatic hypothalamic timing mechanisms:

• Decreased or Increased Psychomotor Activity (Item 9): Captures deviations along the motoric continuum. The scale documents hypoactivity (psychomotor slowing, reduced spontaneous movements, poverty of speech, hypokinesia) and hyperactivity (akathisia-like restlessness, purposeless motor behaviors, picking at bedclothes, uncoordinated attempts to extricate catheters). The MDAS uniquely includes a qualitative sub-categorization noting whether the motor presentation is hypoactive, hyperactive, or mixed.
• Sleep-Wake Cycle Disturbance (Item 10): Quantifies chronobiological desynchronization, ranging from mild daytime somnolence and nighttime awakenings to complete sleep-wake reversal, severe nocturnal insomnia, or persistent daytime stupor.

6. Theoretical Framework

The MDAS is anchored in neurobiological, cognitive neuropsychological, and syndromal psychiatric theories of delirium. Structurally and diagnostically, it was built to align directly with the criteria of the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R and DSM-IV), while remaining highly concordant with modernized DSM-5 criteria. Delirium theory posits that the clinical syndrome represents the final common neurobehavioral pathway of acute, systemic physiological insults acting upon a vulnerable central nervous system.

Neurochemical and Neurotransmitter Imbalance Hypothesis

The core theoretical premise underlying the MDAS items is the balance between central cholinergic neurotransmission and ascending subcortical monoaminergic activity. Acetylcholine plays an indispensable role in maintaining attention, working memory, sensory gating, and rapid REM sleep regulation. Deficits in central cholinergic transmission—whether induced by anticholinergic pharmacology, neurodegenerative cholinergic basal forebrain cell loss, or metabolic failure—directly produce the deficits measured by Items 1 through 5 and Item 10. Conversely, hyperdopaminergic states, often accompanied by dysregulated norepinephrine and serotonin activity, fuel psychomotor agitation, disorganized thought architecture, illusions, and delusions, which are captured by Items 6, 7, 8, and 9.

Network Connectivity and Cognitive Reserve Models

From a cognitive neuroscience perspective, delirium is theorized as an acute disconnection syndrome characterized by functional breakdown within large-scale neurocognitive networks, notably the Default Mode Network (DMN), the Salience Network, and the Central Executive Network. When systemic inflammation (driven by cytokines such as IL-1, IL-6, and TNF-alpha), hypoxia, or metabolic disturbances compromise microvascular integrity and blood-brain barrier function, neural network synchronization falters. Individuals with diminished baseline cognitive reserve (such as those with underlying pre-existing dementia or microvascular ischemic brain disease) lack the compensatory capacity to maintain attentional tracking and executive control under stress, resulting in the acute symptomatic cascade measured by the 10 MDAS items.

7. Validity

The psychometric validity of the MDAS has been rigorously substantiated across diverse clinical populations, including cancer inpatients, palliative care units, geriatric rehabilitation services, surgical intensive care units, and consultation-liaison psychiatry settings.

Construct and Criterion-Related Validity

In the seminal validation investigation conducted by Breitbart et al. (1997) involving hospitalized advanced cancer patients, MDAS scores were compared across three distinct clinical groups: patients meeting DSM-III-R and DSM-IV diagnostic criteria for delirium (mean MDAS score = 14.88 ± 5.76), patients diagnosed with dementia without delirium (mean score = 7.75 ± 3.86), and intact medical controls with neither diagnosis (mean score = 2.05 ± 1.76). Analysis of variance demonstrated highly significant between-group discrimination (p < .0001), demonstrating excellent construct and discriminative validity.

Convergent and Concurrent Validity

Concurrent validity has been verified against established gold-standard instruments:

• Delirium Rating Scale (DRS / DRS-R-98): Breitbart et al. (1997) documented high convergent correlations between the MDAS and the original DRS (Pearson’s r = .88, p < .0001). Subsequent cross-validation studies with the expanded Delirium Rating Scale-Revised-98 (DRS-R-98) demonstrated correlation coefficients consistently exceeding r = .85.
• Mini-Mental State Examination (MMSE): Negative correlations between MDAS total scores and Mini-Mental State Examination scores are routinely documented, typically ranging from r = -.70 to r = -.82 (p < .001). As cognitive capacity declines, MDAS delirium severity proportionally escalates.
• Confusion Assessment Method (CAM): When correlated with the CAM algorithmic status, MDAS scores display strong area under the receiver operating characteristic curve (AUROC) values, consistently reported between .88 and .97 across geriatric and oncology populations.

Diagnostic Accuracy and Cutoff Scores

Receiver operating characteristic (ROC) analyses from the seminal validation sample established that a cutoff score of 13 or higher optimized sensitivity (70.6%) and specificity (93.8%) for identifying delirium against DSM-IV criteria in complex palliative oncology environments. However, cross-cultural and setting-specific investigations have identified alternative optimal thresholds based on the baseline prevalence of cognitive pathology:

• Cutoff ≥ 7 to 8: Frequently recommended in general acute medical, post-cardiac surgical, or general geriatric wards to maximize diagnostic sensitivity (exceeding 90%) for early detection and identification of mild/subsyndromal delirium.
• Cutoff ≥ 10: Commonly utilized in general inpatient psychiatric consultation-liaison settings, balancing sensitivity (~85%) and specificity (~88%).
• Cutoff ≥ 13: Preferred in oncology, advanced palliative hospice cohorts, and populations with high dementia comorbidity, where false positives from underlying cognitive slowing or opioid-induced lethargy must be minimized.

Sensitivity to Clinical Change

The MDAS exhibits exceptional responsiveness to longitudinal clinical resolution. In prospective clinical trials of neuroleptic therapy (e.g., Breitbart et al., 2002; Lawlor et al., 2000), longitudinal MDAS scores tracked significant day-to-day decreases following pharmacological intervention, correlating robustly with the resolution of EEG slowing, improvements in nurse-rated behavioral stability, and patient discharge readiness.

8. Reliability

The MDAS possesses strong reliability characteristics across multiple evaluative dimensions, including internal consistency, inter-rater concordance, and short-interval stability.

Internal Consistency

In the original validation study by Breitbart et al. (1997), the overall scale achieved a Cronbach’s alpha of .91, indicating high internal homogeneity among the 10 constituent items. Subsequent international validation studies have replicated these parameters:

• European validation cohorts: Alpha coefficients typically span between .82 and .89.
• East Asian language validations (Japanese, Korean, Chinese): Cronbach’s alpha coefficients range from .77 to .90, confirming that item covariance remains stable across distinct linguistic structures and hospital cultures.
• ICU and post-operative adaptations: Alphas consistently maintain values between .80 and .86, despite mechanical barriers such as endotracheal intubation.

Inter-Rater Reliability

Because the scale is clinician-administered, inter-rater reliability is vital. In paired simultaneous independent examinations conducted by psychiatrists, research nurses, and palliative care physicians, the inter-rater reliability of the total score has yielded intraclass correlation coefficients (ICC) and Pearson correlation coefficients ranging from .84 to .96 (p < .001). Individual item kappa coefficients (κ) generally range from .65 (for subtle subjective items like sleep-wake cycle disruptions inferred from collateral nursing logs) to .92 (for structured performance tasks such as digit span and orientation).

Test-Retest Stability

Evaluating test-retest reliability in delirium presents a methodological paradox because delirium is, by definition, a fluctuating syndrome. Nonetheless, within short-interval stability designs (evaluations conducted within 2 to 4 hours under stable pharmacological conditions), test-retest correlations range between .75 and .85. This confirms that measurement variability reflects true biological symptom fluctuation rather than psychometric instability.

9. Factor Analysis

Substantial empirical inquiry using both Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) has examined the latent dimensional architecture of the MDAS. Although initially utilized as a unidimensional summary index of delirium severity, psychometric evaluations repeatedly demonstrate that the scale is best characterized by a multi-dimensional construct comprising 2 to 4 latent factors.

Exploratory Factor Solutions

Factor analytical studies across oncology, geriatric, and psychiatric cohorts (e.g., Grassi et al., 2001; Shyamsundar et al., 2009) have predominantly isolated either a two-factor or a three-factor solution:

• The Two-Factor Model:
  • Factor 1: Cognitive/Attentional Impairment. Encompasses Item 1 (consciousness/awareness), Item 2 (disorientation), Item 3 (short-term memory), Item 4 (digit span), and Item 5 (sustained/shifting attention). This factor explains the largest proportion of total variance (typically 40% to 52%), accounting for the cognitive infrastructure of delirium. Item loadings on this factor routinely exceed .70.
  • Factor 2: Neurobehavioral / Psychiatric Manifestations. Comprises Item 6 (disorganized thinking), Item 7 (perceptual disturbances), Item 8 (delusions), Item 9 (psychomotor activity), and Item 10 (sleep-wake cycle). This factor accounts for approximately 12% to 18% of the common variance, reflecting the outward behavioral and perceptual features of the disorder.
• The Three-Factor Model:
  • Factor 1: Core Cognitive Failure (Items 2, 3, 4, 5).
  • Factor 2: Neuropsychiatric / Psychotic Symptoms (Items 6, 7, 8).
  • Factor 3: Arousal / Neurovegetative Regulation (Items 1, 9, 10).

Confirmatory Factor Analysis and Model Fit

Structural equation modeling and CFA evaluations demonstrate that multi-factor models yield superior fit compared to a strictly unidimensional structure. In fit evaluations, a two- or three-factor structure consistently generates root mean square error of approximation (RMSEA) values below .06, comparative fit index (CFI) values exceeding .95, and Tucker-Lewis Index (TLI) metrics above .94, confirming strong model parsimony and structural stability across diverse clinical settings.

10. Instrument / Measurement Tool

The structural characteristics, administration protocols, and scoring guidelines for the MDAS are summarized below:

• Test Type: Clinician-administered neuropsychiatric severity rating scale.
• Administration Format: Direct patient examination combined with behavioral observation and collateral chart/nursing review covering the immediate interview period and the previous several hours.
• Target Population: Hospitalized adult and geriatric patients suspected of or diagnosed with delirium, particularly within oncology, palliative medicine, intensive care, and general medical/surgical settings.
• Item Count: 10 standardized items (with an additional qualitative behavioral sub-typing check for psychomotor presentation).
• Time Required: Approximately 10 to 15 minutes for complete bedside execution.
• Response Scale: 4-point ordinal rating scale (0 to 3) for each item:
  • 0 = None (normal functioning / absent symptom)
  • 1 = Mild (barely noticeable or transient impairment; minimal disruption)
  • 2 = Moderate (undeniable impairment; interview prolonged but not halted)
  • 3 = Severe (pronounced disruption; task impossible or marked behavioral interference)
• Scoring and Quantification Rules:
  • The clinician sums the scores from all 10 items.
  • Total Score Range: 0 to 30.
  • Diagnostic Thresholds: A cutoff score of ≥ 13 is standard in advanced oncology/palliative care. In general medical/geriatric wards, a threshold of ≥ 7 or ≥ 8 is often applied to capture mild cases.
  • Severity Stratification: Scores of 0–6 generally reflect normal status or mild cognitive impairment; 7–12 indicate mild or subsyndromal delirium; 13–18 represent moderate delirium; and 19–30 reflect severe, highly disruptive delirium.
  • Item 9 includes an observational sub-typing descriptor allowing the clinician to classify the episode as: (a) hypoactive, (b) hyperactive, or (c) mixed motoric subtype.

11. Permissions & Fee and Test Year

The Memorial Delirium Assessment Scale was originally published in 1997 by Dr. William Breitbart and co-workers in the Journal of Pain and Symptom Management. The instrument was developed under institutional academic sponsorship at Memorial Sloan Kettering Cancer Center (MSKCC).

• Copyright and Commercial Status: The copyright for the original article and measurement instrument is held by Elsevier Inc. on behalf of the American Academy of Hospice and Palliative Medicine (AAHPM), with intellectual attribution to the developers at MSKCC.
• Permissions and Academic Licensing: The scale is widely considered an open-access clinical and research instrument for non-commercial academic research, institutional hospital quality improvement, and clinical bedside care, provided standard academic citation is given. Commercial entities, pharmaceutical clinical trials, or electronic health record (EHR) proprietary system vendors seeking integration must seek formal licensing and permission through the publisher (Elsevier / RightsLink) or the Department of Psychiatry and Behavioral Sciences at Memorial Sloan Kettering Cancer Center.
• Fee: There are no user fees for individual clinicians, academic investigators, or non-profit educational institutions administering the printed paper-and-pencil scale.

12. References

Breitbart, W., Rosenfeld, B., Roth, A., Smith, M. J., Cohen, K., & Passik, S. (1997). The Memorial Delirium Assessment Scale. Journal of Pain and Symptom Management, 13(3), 128–137. https://doi.org/10.1016/S0885-3924(96)00316-8

Breitbart, W., Tremblay, A., & Gibson, C. (2002). An open trial of olanzapine for the treatment of delirium in hospitalized cancer patients. Psychosomatics, 43(3), 175–182. https://doi.org/10.1176/appi.psy.43.3.175

Grassi, L., Caraceni, A., Beltrami, E., Borreani, C., Zamorani, M., & De Conno, F. (2001). Assessing delirium in cancer patients: The Italian versions of the Delirium Rating Scale and the Memorial Delirium Assessment Scale. Journal of Pain and Symptom Management, 21(1), 59–69. https://doi.org/10.1016/S0885-3924(00)00244-X

Inouye, S. K., van Dyck, C. H., Alessi, C. A., Balkin, S., Siegal, A. P., & Horwitz, R. I. (1990). Clarifying confusion: The Confusion Assessment Method. A new method for detection of delirium. Annals of Internal Medicine, 113(12), 941–948. https://doi.org/10.7326/0003-4819-113-12-941

Lawlor, P. G., Nekolaichuk, C., Gagnon, B., Mancini, I. L., Pereira, J. L., & Bruera, E. D. (2000). Clinical utility, factor analysis, and further psychometric validation of the Memorial Delirium Assessment Scale in patients with advanced cancer. Cancer, 88(12), 2859–2867. https://doi.org/10.1002/1097-0142(20000615)88:12<2859::AID-CNCR28>3.0.CO;2-9

Shyamsundar, G., Raghuthaman, G., Rajkumar, A. P., & Jacob, K. S. (2009). Validation of the Memorial Delirium Assessment Scale in an Indian general hospital setting. General Hospital Psychiatry, 31(6), 565–569. https://doi.org/10.1016/j.genhosppsych.2009.07.003

Trzepacz, P. T., Baker, R. W., & Greenhouse, J. (1988). A symptom rating scale for delirium. Psychiatry Research, 23(1), 89–97. https://doi.org/10.1016/0165-1781(88)90037-6

Trzepacz, P. T., Mittal, D., Torres, R., Kanary, K., Norton, J., & Jimerson, N. (2001). Validation of the Delirium Rating Scale-Revised-98: Comparison with the Delirium Rating Scale and the Cognitive Test for Delirium. The Journal of Neuropsychiatry and Clinical Neurosciences, 13(2), 229–242. https://doi.org/10.1176/jnp.13.2.229

13. Items of the Scale (Questionnaire)