You should discuss the situation with an attorney in your area who is familiar with real estate law and probate and family law. The person may need a guardian to help manage or the incapacity may be serious enough to obtain a court order that will extinguish the life estate.
If the person left a Will the Will will identify who the administrator (executor) of the estate is to be - only this person can anministor the estate. If there is no Will then the state will appoint an administrator (there will be country specific laws relating to how this happens).
In the United States a person is considered an adult at 18 unless they have a mental defect.
When a life tenant dies the life estate is extinguished. A death certificate should be recorded in the land records.
The life estate expires when the life estate owner does and the mineral rights revert to the property owners in fee.
Generally, the probate of the first estate would need to be completed. If the next of kin who died is the only heir and was living when the first person died then that person's estate would need to be probated.
A life estate is a right in property. Rights in property don't go away. The name on the life estate is the person that retains the rights to the life estate.
Nothing happens to the life estate. The life estate remains as long as the person who holds it is still living. Any sale is based on the existence of the life estate. However, if the life estate has not vested, as in the life estate was to be left in a will and they haven't died yet, then the life estate is void.
Mental incompetence is the inability of a person to make or carry out important decisions regarding his or her affairs. An individual is defined as mentally incompetent if he/she is manifestly psychotic or otherwise of unsound mind, either consistently or sporadically, by reason of mental defect. Few examples of such mental defect are retardation, schizophrenia, and dementia. Only a court may declare someone mentally incompetent, after a judicial hearing and testimony from competent medical authority.
An atrial septal defect is a MECHANICAL problem of the heart, a structural defect in the heart itself. With that being said, the answer is no. Usually a defect is corrected by surgical intervention.
If a person dies intestate owning real estate an administration of the estate must be filed in order to vest title to the real estate in the heirs. Until that is done, the heirs don't legally own the property and it cannot be sold or mortgaged.
A person who doesn't care what happens is someone who needs to go to mental health. I'm not trying to be mean, but someone who doesn't care needs help.
The estate can earn dividends on a bank account. The executor is responsible for making sure this happens and it gets included in the estate.