Final answer:
Dementia is the correct answer. It involves impaired intellect or memory lasting at least six months, often featuring symptoms like memory loss and confusion.
Step-by-step explanation:
Impaired intellect or memory that is present for at least six months is called dementia. Dementia is characterised by symptoms such as disruptive memory loss, confusion about time or place, difficulty with planning and executing tasks, poor judgement, and personality changes.
These changes can negatively affect cognition, and one type of dementia that is widely studied is Alzheimer's disease, which was initially researched by Solomon Carter Fuller. Alzheimer's disease symptoms include severe and persistent memory loss, problems with language, problem-solving difficulties, and sometimes changes in mood or behaviour.