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Can a person with dementia sign a will?

The impact of dementia and other neurological diseases can affect everything in a person’s life, from how they work, live and socialise to how they handle financial and end-of-life matters like creating their will.

According to the World Health Organisation, more than 50 million people around the world suffer from dementia, with Alzheimer’s disease being the most common form. Memory loss is a primary symptom of dementia.

Because dementia is a syndrome that disproportionately affects the aged, it can have a significant impact on the matters of one’s final enduring legal document. Under the laws of Queensland and New South Wales alike, wills may be contested if the person creating their will was found to not have the mental capacity to understand what was occurring.

It can be difficult to appropriately ascertain whether a testate is — in that very moment — capable of signing such an important document as a will, regardless of whether damaging physical or neurological conditions are involved.

Legally, if the testate follows the will-signing process faithfully and procures the proper witnesses and signatures, they have fulfilled their role and the resulting documents will hold up under scrutiny.

Having a medical report attesting to their testamentary capacity and an attorney overseeing the process can go a long way toward making a will more dispute-proof, even for someone who had an Alzheimer’s diagnosis.

Estate planning with dementia

Estate planning for someone with Alzhiemer’s or vascular dementia can be complex. Elder law protects the rights of the aged to handle their own financial affairs and health care decisions as long as they are considered to be of sound mind.

This provides people who have received a diagnosis of impending dementia a window of time during which they can complete advance care planning for when they do lose mental capacity, and can appoint people they trust to look after their best interests. They can also make out their will while they are still in full command of their faculties.

A person is considered to still maintain testamentary capacity if at the time they gave instruction to draft their will they:

  • Understand what a will is
  • Understand their financial position generally in regard to assets and property
  • Comprehend who they should leave their estate to, with an appreciation of both Australia inheritance law and their personal preferences
  • Don’t have any had no disorder or delusion of the mind that is influencing them and changing how they dispose of their property


Lack of testamentary capacity is grounds for successfully challenging a will.

Enduring power of attorney and dementia

In most states and territories, any legally competent person can sign an enduring power of attorney, nominating a trusted person to look after their personal financial affairs if they become unable to do so themselves.

This goes beyond a general power of attorney, which is only valid while the signer remains legally competent. An enduring power of attorney is designed to stay in force even if the signer succumbs to dementia and loses their mental capacity.

Wills and dementia

A will instructs the executor on how an estate should be distributed after the signer’s death. It’s necessary for any person making a will to understand its implications. Any person with dementia who needs to make or update their will must do so while they are still competent to sign.

In its most advanced stages, dementia has untold repercussions socially, psychologically and physically. Of course neither seniors with dementia, or their loved ones, may be aware that they are unwell at first, or how quickly the syndrome may be progressing.

It’s during this window of time that dementia patients are unduly susceptible to the outside influence of others attempting to pressure the testate. This “pressure” may be in the form of persuading the testate to change the terms of the will to a given beneficiary’s advantage, for instance.

Similarly, dementia sufferers may not be prepared to sign the will at all – either because the will is not complete, or testate may have other more immediate demands, such as their medical care.

The law does protect against external influence, but “mental capacity” can be tough to define on a universal level. A person with dementia is completely and legally allowed to sign a will. However, after they have passed away, it still may be the case that beneficiaries – or those left out of the will – claim that incompetence or incapacity was at play, thus sending the will into dispute.

Nevertheless, if a person holding an enduring power of attorney, who is present at the signing, declares that the testate was competent and fully understanding of what they are doing, then the will is valid.

Challenging a will for undue influence

A will can be challenged for undue influence by enlisting a lawyer to build a case that your loved one had compromised mental capacity and was illegally coerced or influenced by a third party at the time of the will signing.

If a previous will was in place but suddenly a new will is drawn up that cuts many people out of inheritance and leaves large sums of money or property to a party close to the deceased, it may be suspected thet that person exerted undue influence. Your solicitor can help you build a case and take the will to court in hope of overturning it and reinstating the previous will to probate.

Choosing a will dispute law firm

GMP Contesting Wills is one of the largest private, highly specialised, and focused law firms in the area of will disputes Australia-wide.

If you or someone you love believe mental capacity was in jeopardy during the will-making process, you may be eligible to contest the will. Contact our Will Dispute Lawyers at GMP Contesting Wills today to learn your rights and options.


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Meet the diverse and dynamic team of compensation lawyers and supporting staff that have made this all happen below. Our multi-lingual team can discuss your claims in Arabic, Assyrian, Turkish, Greek, Italian, French, Serbian, Croatian, Armenian, Mandarin, Hindi, Punjabi or Malayalam.

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