Scale balancing pills and a note, symbolizing the choice between overdose and suicide.

Unintentional or Intentional? Understanding Poisoning Deaths in Older Adults

Lena Kashyap in Health & Wellness December 2025 • 4 min read.

"New research sheds light on the critical differences between suicides and deaths of undetermined intent (UnD) in late-middle-aged and older adults, offering potential paths for better prevention and classification."

The rising rates of prescription and illicit drug poisoning deaths, particularly among individuals aged 50 and older, present a complex challenge. Often, these deaths are classified as either suicides or deaths of undetermined intent (UnD), a category that lacks definitive evidence of intentional self-harm. Distinguishing between these classifications is crucial for understanding the underlying causes and implementing effective prevention strategies.

Coroners and medical examiners (CMEs) play a vital role in determining the manner of death, categorizing it as accidental, suicide, or UnD. While forensic autopsies provide valuable insights, the absence of corroborative evidence, such as suicide notes or prior expressions of suicidal intent, can complicate the process, especially in cases involving drug intoxication. This complexity contributes to the substantial proportion of deaths classified as UnD, highlighting the challenges in accurately assessing intent in poisoning fatalities.

A new study delves into the factors that differentiate suicide from UnD poisoning deaths in older adults. By analyzing data from the 2005–2015 U.S. National Violent Death Reporting System (NVDRS), researchers compared the characteristics, risk factors, and toxicology results of these two groups, shedding light on the potential for misclassification and informing strategies for more accurate death determination.

Key Differences Between Suicide and Undetermined Intent in Poisoning Deaths

Scale balancing pills and a note, symbolizing the choice between overdose and suicide.

The research highlights significant differences between individuals who died by suicide and those whose deaths were classified as UnD. Those who left suicide notes were more likely to have a history of depression, physical health problems, and other life stressors. In contrast, UnD cases were characterized by a lower prevalence of mental health issues and life stressors but a higher likelihood of substance use and related health problems. UnD cases also showed a greater likelihood of testing positive for opioids and cocaine, but were less likely to test positive for antidepressants.

These findings suggest that many deaths classified as UnD may, in fact, be unintentional overdoses. The study underscores the need for improved accuracy in determining the intent and manner of death, as well as targeted interventions to address substance use and prevent both intentional and unintentional poisoning deaths.

Mental Health and Life Stressors: Suicide decedents with notes reported higher rates of depression and life stressors.
Substance Use: UnD cases were more likely to have substance use problems.
Toxicology Results: UnD cases showed higher rates of opioid and cocaine positivity.
Racial Disparities: Black individuals were more than twice as likely to be classified as UnD compared to non-Hispanic Whites.

The study challenges the assumption that all UnD cases are simply unclassifiable suicides, suggesting that a significant portion may be unintentional overdoses. This distinction is crucial for informing public health interventions and prevention strategies. By recognizing the unique characteristics and risk factors associated with UnD cases, we can develop targeted approaches to address substance use, improve access to treatment, and ultimately reduce the number of preventable deaths.

Recommendations for Moving Forward

The study highlights the need for a multi-faceted approach to address poisoning deaths in older adults. This includes improving the accuracy of death classification, implementing targeted substance use interventions, and addressing the racial disparities in UnD classifications. By recognizing the distinct characteristics of suicide and UnD cases, we can develop more effective prevention strategies and ultimately save lives.

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This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1017/s1041610218001540, Alternate LINK

Title: Poisoning Deaths Among Late-Middle Aged And Older Adults: Comparison Between Suicides And Deaths Of Undetermined Intent

Subject: Psychiatry and Mental health

Journal: International Psychogeriatrics

Publisher: Cambridge University Press (CUP)

Authors: Namkee G. Choi, Diana M. Dinitto, C. Nathan Marti, Bryan Y. Choi

Published: 2018-10-24

Everything You Need To Know

What are the key differences between suicide and undetermined intent (UnD) poisoning deaths in older adults?

The key differences lie in several factors. Suicide cases, especially those with suicide notes, are often linked to a history of depression, physical health problems, and other significant life stressors. In contrast, deaths classified as UnD tend to have a lower prevalence of mental health issues and stressors but a higher likelihood of substance use problems. Toxicology results also differ, with UnD cases showing a higher likelihood of testing positive for opioids and cocaine, but less likely for antidepressants. These distinctions are crucial for differentiating between intentional self-harm and potential unintentional overdoses.

How do Coroners and Medical Examiners (CMEs) determine the manner of death in poisoning cases, and what challenges do they face?

Coroners and Medical Examiners (CMEs) play a vital role in determining the manner of death, classifying it as accidental, suicide, or UnD. They rely on forensic autopsies, which provide valuable insights. However, the absence of corroborative evidence, such as suicide notes or prior expressions of suicidal intent, complicates the process, particularly in cases involving drug intoxication. This can lead to a substantial proportion of deaths being classified as UnD, highlighting the challenges in accurately assessing intent in poisoning fatalities, as they must carefully consider all available evidence to make a determination.

What role does substance use play in deaths classified as undetermined intent (UnD) compared to suicide cases?

Substance use is a significant differentiating factor. UnD cases show a higher prevalence of substance use problems compared to suicide cases. Furthermore, toxicology results reveal that UnD cases are more likely to test positive for opioids and cocaine. This suggests that a considerable number of UnD deaths might be unintentional overdoses rather than intentional acts of self-harm. This underscores the importance of addressing substance use issues through targeted interventions to prevent both intentional and unintentional poisoning deaths.

What are the implications of racial disparities in the classification of poisoning deaths?

The study highlights racial disparities in UnD classifications, where Black individuals are more than twice as likely to be classified as UnD compared to non-Hispanic Whites. This disparity suggests potential biases or differences in access to care and resources. It calls for a closer examination of the factors contributing to these disparities, emphasizing the need for more equitable approaches in both death classification and preventative strategies. Addressing these disparities is crucial for ensuring fair and effective public health interventions.

What are some of the recommendations for addressing poisoning deaths in older adults, based on the study findings?

The study emphasizes a multi-faceted approach. Firstly, it recommends improving the accuracy of death classification, which can be achieved by enhancing the investigation process and gathering more comprehensive evidence. Secondly, it suggests implementing targeted substance use interventions to address the high prevalence of substance use problems in UnD cases. Finally, the study highlights the need to address racial disparities in UnD classifications to ensure equitable outcomes. By adopting these strategies, it is possible to develop more effective prevention programs and save lives. The focus must be on understanding the distinct characteristics of both suicide and UnD cases to tailor interventions effectively.