the frontal lobe
Generally accepted key functions of the brains frontal lobe affected by dementia are as follows:
Voluntary movement: this includes walking, running and balance. These functions may be affected to a varying degree in different individuals and, as the dementia diseases progress, individuals may need to rely on caregivers or mechanical aids.
Behaviour: confusion in emotional responses sometimes exhibits itself as a contradictory expression. For example, an individual may smile when feeling sad or might use an unexpected tone when welcoming another individual. Displays of aggression and excessive emotional responses with no apparent catalyst may also be evident in some individuals. Personality can alter significantly and can be alarming for family and friends. Individuals may 'change' or exhibit Jekyll and Hyde personalities and may lose their inhibitions. Socially inappropriate behaviour and unwanted sexual advances are not uncommon, even in sufferers of advanced age.
An octogenarian individual I am acquainted with (most recently a man of impeccable manners and gentlemanly behaviour) appeared naked with an erection in a guests' bedroom in the early hours of the morning. He removed the covers and attempted to climb into bed with the astonished guest. Fortunately, his wife heard the distressed screech, came rushing to the rescue and removed her confused husband from the scene. Prior to his memory of the intended encounter disappearing into a black hole, the individual was not in the least embarrassed by the event and referred to the scene during a later discussion with his GP and therapist as 'the incident'. His remarkable wife decided not to follow her impulse to either shoot him or divorce him and managed to look past the disease at the man himself and continue to care for him. What a woman!
Interpretation of feelings and response to stimulations may be 'politically incorrect', illogical and out of character, and frequently they produce totally unexpected outcomes.