Dementia

Mental derangement accompanied by general derangement of faculties.' Characterized by forgetfulness, inability to follow any train of thought, and indifference to passing events.' An impaired state of the mental powers, feebleness of mind caused by disease and not accompanied by delusion (g. v.) or uncontrollable impulse. < May exist without complete prostration.

Senile dementia

That peculiar decay of the mental faculties which occurs in extreme old age, and in many cases much earlier, whereby the person is reduced to second childhood and sometimes becomes wholly incompetent to enter into a binding contract or even to execute a will. It is the recurrence of second childhood by mere decay.' See further Insanity.