Cognitive decline usually refers to a progressive loss of cognitive or mental ability associated with aging. While the brain undoubtedly changes as the body ages as a whole, there is not just one single pattern for the effect of aging on everyone's cognitive ability. Most commonly, mental aging is associated with generally harmless memory problems and forgetfulness. Other changes that may occur with cognitive decline include decreases in reaction time, language skills, and visual-spatial ability. For the majority of older people, this decline is considered a normal part of the aging process and is not an usually an indication of a disease such as Alzheimer's.
Decreases in memory are often cited as one feature of cognitive decline. Typically, memory loss is slow or non-existent through age 60 and may accelerate afterward, particularly after the age of 70. At the age of 70, only about 40 percent of people have the memory ability they had in their thirties. The other 60 percent have some memory impairment, a condition sometimes referred to as benign senescent forgetfulness, and that doesn't greatly affect problem-solving or language skills. At the age of 70, some 30 percent of the impaired group may be in the early stages of Alzheimer's.
Diminished memory due to aging typically affects only the short-term memory. This may make it more difficult for people with cognitive decline to absorb new information, particularly when it is communicated verbally. Long-term memory, or memories that are many years old, aren't usually affected. Some older people may even recall long-term memories better than when they were younger.
Like short-term memory, general cognitive abilities such as planning and problem-solving also begin to decline around the age of 60, with the decline becoming more rapid after 70. Not everyone experiences the same features of cognitive decline, though, and some experience no symptoms at all or even an improvement. While the reasons for this aren't clear, they likely have to do with education background, genetics, and environment. Diminished sleep may be more common, as more physical complaints make prolonged, comfortable sleep more difficult. Other age-related changes in the brain can make sleep less restful.
It has been debated whether overall intelligence is affected by cognitive decline. While nonverbal intelligence appears to decline with age, verbal intelligence usually tends to remain stable. Other tests show that some aspects of cognitive performance may become better with age. What seems most clear is that, when in good overall health and in a stimulating environment, aging people can continue to learn and achieve as they grow older.