Dr. Morisky’s Breakthrough in Medication Adherence: Revolutionizing Assessment with Intentional and Unintentional Non-Adherence

In the realm of healthcare, ensuring patients adhere to their prescribed medication regimens is a critical challenge, particularly for chronic conditions like diabetes or hypertension. Dr. Donald E. Morisky’s development of the 8-item Morisky Medication Adherence Scale (MMAS-8) has been a game-changer in understanding why patients may not take their medications as prescribed. His groundbreaking work, particularly in two pivotal studies published in 2010 and 2015, introduced a novel approach to categorizing low adherence into intentional and unintentional non-adherence based on patients’ responses. This distinction—intentional non-adherence (driven by conscious choices, like avoiding side effects) versus unintentional non-adherence (driven by forgetfulness)—has significantly improved the validity of the MMAS-8, enabling more precise interventions to improve patient outcomes. In this blog, we’ll explore how Dr. Donald Morisky’s breakthrough in these studies transformed adherence research and its implications for healthcare.
The MMAS-8: A Tool to Understand Adherence
The MMAS-8 is a concise, self-reported questionnaire with eight items designed to assess medication-taking behaviors. It includes seven yes/no questions and one 5-point Likert scale question, capturing both intentional behaviors (e.g., “ Have you ever cut back or stopped taking your medication without telling your doctor, because you felt worse when you took it?”) and unintentional behaviors (e.g., “Do you sometimes forget to take your medication?”). Scored from 0 to 8, a score of 8 indicates high adherence, 6 to <8 medium adherence, and <6 low adherence. Dr. Morisky’s innovation lies in leveraging these items to distinguish between two types of non-adherent behaviors among low adherers, enhancing the scale’s ability to pinpoint the root causes of non-adherence.
Dr. Donald Morisky's 2010 Breakthrough: Validating MMAS-8 in Diabetes Care
In a landmark 2010 study published in Diabetes Research and Clinical Practice, Dr. Morisky and colleagues validated the MMAS-8 in patients with type 2 diabetes, marking a significant step forward in adherence research. The study, titled “Validation and Reliability of an Eight-Item Morisky Medication Adherence Scale (MMAS-8) in Type 2 Diabetes,” demonstrated the scale’s reliability (Cronbach’s α ≈ 0.83) and validity in a diverse cohort of diabetes patients. Most notably, it introduced a groundbreaking perspective by using factor analysis to identify two distinct dimensions of non-adherence among those with low adherence scores (<6):
• Intentional Non-Adherence: When the majority of a patient’s MMAS-8 responses indicated behaviors not related to forgetfulness, such as deliberately stopping medication due to side effects, beliefs about its necessity, or feeling better/worse. For example, responses to items like “ When you feel like your symptoms are under control, do you sometimes stop taking your medication?” reflect intentional choices.
• Unintentional Non-Adherence: When the majority of responses pointed to forgetfulness or carelessness, such as answering “yes” to “Do you sometimes forget to take your medication?” or “ Did you take your medication the last time you were supposed to take it?”
This distinction was a major breakthrough because it allowed researchers and clinicians to categorize low adherers based on the why behind their behavior. The study found that intentional non-adherence was often tied to patient beliefs (e.g., skepticism about medication efficacy), while unintentional non-adherence was linked to logistical barriers like forgetting doses. By separating these behaviors, the MMAS-8 provided a clearer picture of adherence challenges, improving its construct validity—the degree to which the scale accurately measures what it intends to (i.e., adherence behaviors).
How It Improved Validity: By dividing low adherers into intentional and unintentional categories, the MMAS-8 better captured the multidimensional nature of non-adherence. Traditional adherence measures often treated non-adherence as a single construct, missing the nuanced reasons behind it. The 2010 study’s factor analysis confirmed that MMAS-8 items align with these two distinct constructs, ensuring the scale reflects real-world patient behaviors more accurately. This enhanced validity allows for more targeted interventions—education or counseling for intentional non-adherers and reminders or pill organizers for unintentional non-adherers.
Citation: Morisky, D. E., et al. (2010). Validation and reliability of an eight-item Morisky Medication Adherence Scale (MMAS-8) in type 2 diabetes. Diabetes Research and Clinical Practice, 90(2), 216–221. Link.
Dr. Donald Morisky’s 2015 Study: Extending the Breakthrough to Psychiatric Care
Dr. Morisky’s work continued to evolve in a 2015 study published in the International Journal of Clinical and Health Psychology, titled “Psychometric Properties of the Eight-Item Morisky Medication Adherence Scale (MMAS-8) in a Psychiatric Outpatient Setting.” Conducted with 967 psychiatric outpatients in Spain, this study further validated the MMAS-8’s ability to distinguish intentional and unintentional non-adherence. Using the Spanish version of the scale, researchers found that among patients with low adherence (MMAS-8 score <6), responses could be categorized based on whether the majority indicated intentional behaviors (e.g., avoiding medication due to side effects or stigma) or unintentional behaviors (e.g., forgetfulness due to complex regimens).
The study reported adequate construct validity and a single-factor structure for overall adherence, but its analysis of low adherers echoed the 2010 findings by identifying intentional and unintentional non-adherence as distinct patterns. For example, psychiatric patients who intentionally skipped doses often cited concerns about dependency or social stigma, while unintentional non-adherence was linked to cognitive challenges associated with mental health conditions. The MMAS-8’s correlation with the Drug Attitude Inventory further supported its validity in capturing these nuanced behaviors.
How It Improved Validity: The 2015 study reinforced the MMAS-8’s ability to differentiate intentional and unintentional non-adherence in a new population—psychiatric patients—enhancing its generalizability. By categorizing low adherers based on response patterns, the scale provided a more precise measurement of adherence barriers, improving its construct validity across diverse clinical contexts. This allowed clinicians to tailor interventions, such as addressing stigma for intentional non-adherers or simplifying regimens for those forgetting doses, thereby increasing the scale’s practical utility.
Citation: De las Cuevas, C., et al. (2015). Psychometric properties of the eight-item Morisky Medication Adherence Scale (MMAS-8) in a psychiatric outpatient setting. International Journal of Clinical and Health Psychology, 15(2), 121–129. Link.
Why This Breakthrough Matters
Dr. Morisky’s approach to dividing low adherers into intentional and unintentional categories revolutionized adherence research for several reasons:
1. Enhanced Precision in Measurement: By recognizing that non-adherence is not a monolithic issue, the MMAS-8 captures the underlying reasons for non-adherent behavior. This improves the scale’s construct validity, as it aligns more closely with the complex reality of patient decision-making and challenges.
2. Targeted Interventions: Understanding whether non-adherence is intentional or unintentional allows healthcare providers to design specific interventions. For intentional non-adherers, education, counseling, or addressing side effects can help. For unintentional non-adherers, tools like reminders, apps, or simplified regimens are more effective. This precision enhances patient outcomes.
3. Broader Applicability: The 2010 and 2015 studies demonstrated that the MMAS-8’s categorization applies across different conditions—diabetes and psychiatric disorders—making it a versatile tool. Subsequent studies in cancer, chronic pain, and community settings have built on this framework, further validating its utility.
4. Improved Scoring Validity: Traditional adherence scales often assign a single score without distinguishing reasons for non-adherence, which can obscure intervention strategies. By analyzing response patterns to categorize low adherers, the MMAS-8 ensures that scores reflect distinct behavioral constructs, increasing the reliability and validity of the results.

The Lasting Impact
Dr. Morisky’s 2010 and 2015 studies laid the foundation for a more nuanced understanding of medication adherence by categorizing low adherers into intentional and unintentional groups based on MMAS-8 response patterns. This breakthrough has improved the scale’s validity by ensuring it captures the multidimensional nature of non-adherence, enabling clinicians to address specific barriers with tailored interventions. From diabetes to psychiatric care, the MMAS-8’s ability to distinguish between intentional choices and forgetfulness has reshaped how we approach patient care, making it a cornerstone of adherence research.

Note: This blog is based on research available as of June 11, 2025, at 10:41 PM PDT.