Textbook on Geriatric Psychiatry states that a decline in cognitive functioning with age occurs in several areas, including intelligence, ability to maintain attention, memory, learning, visuospatial functions, and psychomotor functions, but these factors do not occur uniformly across all areas. Elderly individuals also develop significant changes in vision and hearing. With aging, the heart, blood vessels, and respiratory, gastrointestinal, hematologic, immune, renal, and endocrine systems also develop considerable changes in their functional ability, along with changes in pharmacokinetics and pharmacodynamics. In addition, there are "geriatric syndromes," including falls, urinary incontinence, frailty, polypharmacy, and, among many elderly persons, the development of dementia. Today, in geriatric psychiatry, the study of genetics and genetic testing is a rapidly changing field. Along with gene-specific treatments, these changes may improve the accuracy of diagnosis. Patients who are 85 or older—described as the "fourth age"—and who develop a large portion of observed age differences are no longer considered as being in a province of "happy gerontology." For all elderly people who reach this extreme age, the text recommends that the psychiatric interview be paced so that the older person has enough time to respond to the questions asked.