Know the Law: Estate Planning with Dementia Diagnosis

Photo of Cameron Cantelmo
Cameron J. Cantelmo
Associate, Litigation Department
Published: Union Leader
December 20, 2025

Q: My mother is getting up there in years and has finally expressed interest in establishing an estate plan.  However, she was recently diagnosed with dementia.  Will this have any impact on her ability to create an estate plan?

A: A dementia diagnosis does not automatically prevent your mother from creating a valid estate plan, but it does increase the need for documentation.  Under New Hampshire law, anyone signing a will or trust must possess “testamentary capacity” at the moment of signing.  Courts determine capacity by applying four questions.

First, did the person understand the nature of the act?  The signer must recognize that they are executing a document that directs the distribution of their property after death.

Second, could the person recall the general nature and extent of their property? The signer must only have a broad understanding; for example, knowing they own a house, car, and bank accounts.

Third, could the person recognize their closest relatives?  The signer must be able to identify immediate family members who would be considered potential heirs.

Fourth, was the person able to decide how their property should be distributed among those people or others?  This means they must be able to connect their understanding of their assets with their understanding of the individuals who might inherit.

If the answer to any of these questions is “no,” and the will or trust is later contested, a court may invalidate the document.  However, a dementia diagnosis alone does not resolve these questions.  Individuals in early and moderate stages of dementia may still retain enough clarity to satisfy the legal standard. Some people with dementia diagnoses also experience “lucid intervals,” during which they temporarily possess the requisite capacity.

Because a diagnosis increases the likelihood of future challenges, it is essential to take additional precautions to ensure the documents validity.  It is critical to work with an experienced estate planning attorney in these circumstances, and to ensure that the attorney is fully aware of the diagnosis.  In some cases, the attorney may recommend a medical capacity evaluation prior to execution of any estate planning documents.  The attorney may even suggest filing a petition to have the will proven while the testator is still alive under a special procedure provided for under New Hampshire statute.

The most important step is not to delay.  Capacity issues typically worsen over time, and early planning with a qualified estate planning attorney reduces legal uncertainty and family conflict.  Encouraging your mother to proceed now, while clearly documenting her understanding, gives her the best chance of ensuring that her wishes are honored.

 

Know the Law is a bi-weekly column sponsored by McLane Middleton.  Questions and ideas for future columns should be emailed to knowthelaw@mclane.com.  Know the Law provides general legal information, not legal advice.  We recommend that you consult a lawyer for guidance specific to your particular situation.