Dementia is a loss of brain function. It’s not a single disease, but instead refers to a group of illnesses that involve memory, behavior, learning, and communication problems. The problems are progressive, which means they slowly get worse.
Decline in memory and cognitive function are considered a normal consequence of aging and different from dementia. Terms like “Age-Consistent Memory Decline” and “Age-Related Cognitive Decline (ARCD)” have been used to describe these normal developmental changes which may or may not progress into dementia. Although many individuals with ARCD go on to develop dementia of the Alzheimer’s type, brain imaging and risk factors for ARCD suggest cerebral differences.
While ARCD is not considered a disease, experts differ on whether it’s related to dementia or is a distinct entity. People with ARCD experience specific symptoms, such as deterioration in memory, learning, attention, concentration, use of language, and other mental functions. In normal elderly adults, cognitive performance generally remains stable over many years, with only slight declines in short-term memory and reaction times.
Symptoms and Diagnosis of Cognitive Decline and Dementia
Because there have been so many terms and diagnosis standards with regards to cognitive decline and dementia, understanding the terminology can be confusing. In order to provide some clarification, researchers developed the Global Deterioration Scale for assessment of primary degenerative dementia. In this model, the phases and characteristics of cognitive decline are divided into seven stages:
- No cognitive decline. Normal phase. No subjective memory complaints.
- Very mild decline. Forgetfulness phase. Some subjective memory complaints such as forgetfulness.
- Mild decline. Early confusional phase. First real evidence of cognitive problems.
- Moderate decline. Late confusional phase. Decreased knowledge about current and recent events.
- Moderate severe decline. Early dementia phase. Dependence on other for survival. Decline in abilities of self-care.
- Severe decline. Middle dementia phase requiring moderate to maximal assistance. Increased disorientation.
- Very severe decline. Late dementia phase. Unable to verbally communicate with loss of psychomotor skills.
The further you delve into literature about cognitive impairment and dementia, the more definitions appear. With so many different terms for similar disorders, learning about the various disorders becomes difficult.
Part of the confusion is due to the fact that there are two basic diagnostic books used to diagnose mental health problems, and they each use somewhat different terminology. These two manuals, the ICD-10 Classification of Mental and Behavioral Disorders and the Diagnostic and Statistical Manual of Mental Disorders (DSM-V), have varying differences as you can see in the information that follows. These two books, called the “ICD-10” and the “DSM-V” for short, are considered the bibles of diagnostic mental health manuals among mental health professionals.
The Middle Stages of Cognitive Impairment
In an effort to clarify the stages of cognitive decline, authorities have suggested several terms for a middle categories of cognitive impairment, including:
- Mild cognitive impairment
- Mild neurocognitive disorder
- Age-related cognitive decline
- Mild cognitive disorder
Mild Cognitive Impairment
The diagnosis of mild cognitive impairment (MCI) is difficult and controversial. Originally, the term was coined in the ICD-10 to describe a condition that may or may not eventually lead to dementia. However, research has suggested that people with MCI can have a more rapid decline in cognitive function than those without it, but a less rapid decline than patients with mild Alzheimer’s disease.
Mild Neurocognitive Disorder
The DSM-IV lists another cognitive disorder called “mild neurocognitive disorder.” The essential feature is the development of impairment in neurocognitive functioning that is due to a general medical condition. By definition, the level of cognitive impairment and the impact on everyday functioning is mild. Individuals with this condition have a new onset of deficits in at least two areas of cognitive functioning, such as disturbances in memory, executive functioning, attention or speed of information processing, perceptual motor abilities, or language.
Age-Related Cognitive Decline
According to the DSM-IV, age-related cognitive decline (ARCD) is characterized by memory loss without other cognitive problems. If memory deficit is present but the other diagnostic criteria for dementia are not, a diagnosis other than dementia should be considered.
According to the DSM-IV, ARCD represents cognitive changes that are within normal limits given the person’s age. ARCD is characterized by a decline in only one of the five broad neuropsychologic domains associated with dementia: memory and learning; attention and concentration; thinking; language; and visuospatial functioning. According to the International Psychogeriatric Association, additional criteria should be met to make a diagnosis of ARCD. These criteria include the report of cognitive decline from a reliable source, a gradual onset of at least six months’ duration and a score of more than one standard deviation below the norm on a standardized neuropsychologic test.
Mild Cognitive Disorder
A disorder similar to ARCD is described as “mild cognitive disorder” in the ICD-10. The diagnosis of mild cognitive disorder can be made if the cognitive decline is temporally related to cerebral or systemic disease. No test can detect mild cognitive impairment. Instead, the disorder is diagnosed by excluding other conditions that might be causing the signs and symptoms. Experts say that the diagnosis of ARCD should be considered if cognitive impairment is not considered temporary.
Cognitive Decline
The definitions of and the distinctions between mild cognitive disorder, ARCD, and mild cognitive impairment are controversial. Referral for more extensive neuropsychologic testing, with follow-up intervals of six to nine months, is warranted in patients with mild or borderline cognitive deficits.
People sometimes believe they are having memory problems when there are no actual decreases in memory performance. Therefore, assessment of cognitive function requires specialized professional evaluation. Psychologists and psychiatrists employ sophisticated cognitive testing methods to detect and accurately measure the severity of cognitive decline. However, many of the tests used in research to demonstrate age-related decline in executive functioning (processes thought to control other cognitive operations) have been criticized by mental health professionals for not going far enough in differentiating these control functions from other processes. It’s useful to consider these limitations of testing.
Types of Dementia
Dementia is a deterioration of intellectual function and other cognitive skills. Dementia may involve progressive deterioration of thinking, memory, behavior, personality and motor function. There are many types of dementia, including Alzheimer’s dementia, vascular dementias, Parkinson disease, Lewy body dementia, alcohol-related dementia, and Pick disease. The main risk factor for dementia is age. Dementia is caused by degeneration in the cerebral cortex including death of brain cells, conditions that impair the vascular or neurologic structures of the brain.
Senile dementia, also called Alzheimer’s type (DAT), is the mental deterioration (loss of intellectual ability) that is associated with old age. Senile dementia is different from vascular dementia, which is the type of dementia primarily referred to here.
Vascular dementia (VAD) is a common form of dementia in older persons that is due to cerebrovascular disease, usually with stepwise deterioration. There are a number of different types of VAD. Two of the most common are multi-infarct dementia and Binswanger’s disease. Multi-infarct dementia is the most common form of VAD. Multi-infarct dementia is associated with atherosclerosis. Binswanger’s disease is a progressive neurological disorder characterized by injuries to the blood vessels supplying the deep white-matter of the brain.
VAD can be caused in several different ways. Most commonly there is blockage of small blood vessels (arteries) deep within the brain. The risk factors for VAD are high blood pressure, high cholesterol, diabetes and heart rhythm problems. Treatment of vascular dementia is aimed at reducing the risk factors including stroke, high blood pressure, diabetes, high cholesterol and heart disease.
VAD is the second most common form of dementia after Alzheimer’s disease. The condition is not a single disease; it is a group of syndromes relating to different vascular mechanisms. VAD is preventable; therefore, early detection and an accurate diagnosis are important. Patients who have had a stroke are at increased risk for vascular dementia.
Diagnosing dementia can be challenging, partially because there can be considerable overlap of the different types. The DSM-V criteria for the diagnosis of dementia requires the presence of multiple cognitive deficits in addition to memory impairment. Early in the disease, memory impairment may be the only clinical finding, and this single finding would not meet the diagnostic criteria for dementia. In order to fulfill DSM-V criteria, cognitive impairment must be of the degree that social or occupational function is reduced, with the functional impairment representing a decrease in the patient’s normal ability.
Remember that many conditions have symptoms similar to dementia, so it’s important not to assume someone has dementia because some of the symptoms are present. Strokes, depression, alcoholism, infections, hormone disorders, nutritional deficiencies and brain tumors can all cause dementia-like symptoms. Many of these conditions can be successfully treated but it’s important to get started as soon as possible.
Randi Fredricks, Ph.D.
References
American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision. Washington, DC: American Psychiatric Association, 2022.
World Health Organization. The ICD-10 Classification of Mental and Behavioural Disorders. Genevea, Switzerland: World Health Organization, 2021.
Mountrose, Phillip and Mountrose, Jane. Getting Thru to Your Emotions with EFT: Tap into Your Hidden Potential with the Emotional Freedom Techniques. Sacramento, CA: Holistic Communications, 2007, p. 47.
Smith AD. Prevention of dementia: a role for B vitamins? Nutr Health 2006;18(3): 225–6.
Lau FC, Shukitt-Hale B, Joseph JA. Nutritional intervention in brain aging: reducing the effects of inflammation and oxidative stress. Subcell Biochem 2007;42: 299–318.
Bird TD. Alzheimer’s Disease and Other Primary Dementias. In Braunwald E, et al., editors. Harrison’s principles of internal medicine, vol. 2, ed. 15, New York: McGraw Hill, 2001. p. 2394–95.
Smith GE, Petersen RC, Parisi JE, Ivnik RJ. Definition, course, and outcome of mild cognitive impairment. Aging Neuropsychol Cogn 1996;3: 141–7.
Craik FIM, Salthouse TA. Handbook of Aging and Cognition. Hillsdale, NJ: Erlbaum, 1992.
Crook, TH. Diagnosis and treatment of memory loss in older patients who are not demented. In: Levy R, Howard R, Burns A. (eds). Treatment and care in old age psychiatry. London: Wrightson Biomedical Publishing, 1996, p. 95–111.
Larrabee GJ. Age-associated memory impairment: definition and psychometric characteristics. Aging, Neuropsychology, and Cognition 1996;3: 118–31.
Youngjohn JR, Crook TH. Stability of everyday memory in age-associated memory impairment: A longitudinal study. Neuropsychology 1993;7: 406–16.
Ball LJ, Birge SJ. Prevention of brain aging and dementia. Clin Geriatr Med 2002 Aug;18(3): 485–503.
Smith G, Ivnik RJ, Peterson RC, Malec JF, Kokmen E, Tangalos E. Age-Associated Memory Impairment diagnoses: Problems of reliability and concerns for terminology. Psychology and Aging 1991;6: 551–8.
Levy R. Aging-associated cognitive decline. Working Party of the International Psychogeriatric Association in collaboration with the World Health Organization. Int Psychogeriatr 1994;6: 63–8.
Rubin EH, Storandt M, Miller JP, Kinscherf DA, Grant EA, Morris JC, Berg L. A prospective study of cognitive function and onset of dementia in cognitively healthy elders. Arch Neurol 1998;55(3): 395–401.
Reisberg B, Ferris SH, de Leon MJ, Crook T. The Global Deterioration Scale for assessment of primary degenerative dementia. Am J Psychiatry 1982 Sep;139(9): 1136–9.
Ferris SH, Kluger A. Commentary on age-associated memory impairment, age-related cognitive decline and mild cognitive impairment. Aging Neuropsychol Cogn 1996;3: 148–53.
