Our own reactions may inadvertently add to the person’s lack of mental capacity. I have witnessed many conversations between a person with dementia, a caregiver and another, where the caregiver answers on behalf of the person, or completes their sentences for them — all meant kindly, with no intent to harm, but disabling to the person they care for, nonetheless.
For a person with dementia, feelings are often uppermost. In situations in which they feel fearful, anxious, bored, confused, frustrated, in pain or angry, the feelings of isolation and/or helplessness that the person experiences may find different outlets. The words they then use may not relate to the actual conversation, but instead, include those that reflect familiar, well-rehearsed social norms, or those that transmit their fear, dissatisfaction or frustration at the challenges they are facing.
A person might even swear, despite their normal good manners. They may use paralanguage to communicate their feelings, bypassing words altogether, meaning that petulance, physical force, annoyance or anxiety spill over; or conversely, they may retreat into detachment and passivity.