The DSM-V uses the term neurocognitive disorder instead of dementia when diagnosing degenerative cognitive conditions that primarily influence older adults. Neurocognitive disorders are categorized as major or mild, and dementias are classified as major neurocognitive disorders. When diagnosing a major neurocognitive disorder, the subtype is identified as Alzheimer’s disease, frontotemporal lobar degeneration, human immunodeficiency virus (HIV) infection, Huntington’s disease, Lewy body disease, Parkinson’s disease, prion disease, vascular disease, multiple etiologies, or unspecified. Major neurocognitive disorders are also categorized by the presence or absence of behavioral disturbance and level of severity (mild, moderate, or severe). Cognitive deficits must not be exclusively associated with delirium or better explained by another mental disorder (APA, 2013).
Major neurocognitive disorders are characterized by a significant cognitive decline from a previous level of performance in at least one of the following domains: complex attention, executive function, language, learning and memory, perceptual-motor, or social cognition. The cognitive decline is identified by the individual, knowledgeable informant, or clinician and is documented by neuropsychological testing or quantified cognitive assessment. The cognitive deficits and decline must interfere with daily functioning, specifically instrumental activities of daily living (IADLs) or activities of daily living (ADLs) (APA, 2013). IADLs and ADLs are listed in below.
- Housecleaning and home maintenance
- Managing communication
- Managing finances
- Managing medications
- Shopping and meal preparation
- Transportation and shopping
- Ambulating, transferring, and positioning
- Personal hygiene
- Toileting (Edemekong et al., 2023)
Determination of the appropriate subtype of major neurocognitive disorders enables clinicians to establish the most appropriate treatment plan. Each subtype is discussed below.
Major Neurocognitive Disorder Due to Alzheimer’s Disease
Alzheimer’s disease is characterized by an insidious onset, gradual progression, and impairment in two cognitive domains (complex attention, executive function, language, learning and memory, perceptual motor, and social cognition). Alzheimer’s disease is probable if genetic testing or family history is positive or if evidence of learning and memory and at least one other cognitive domain impairment is present, and the course of cognitive decline is gradual, steady, and progressive. Often, behavioral and psychological symptoms, such as irritability, agitation, and wandering, are present and create distress, especially for caregivers (APA, 2013).
The mean duration of survival after a diagnosis of Alzheimer’s disease is approximately ten years; however, some individuals may live up to 20 years after diagnosis. Memory loss develops early in the progression of Alzheimer’s disease and adversely influences the ability to function independently, but social functioning and procedural memory are retained for a longer time. In late-stage Alzheimer’s disease, people experience incontinence, gait disturbance, and dysphagia. Diagnosis may be confirmed by post-mortem histological examination and will reveal cortical atrophy, amyloid-predominant neuritic plaques, and tau-predominant neurofibrillary tangles in the brain (APA, 2013; Cummings, 2021; Silva et al., 2021).
Major Neurocognitive Disorder Due to Frontotemporal Lobar Degeneration
Frontotemporal dementia is characterized by an insidious onset, gradual progression, and either a behavioral or a language variant. Frontotemporal dementia with a behavioral variant requires a significant decline in the social cognition domain and the executive functioning domain and at least three of the following behavioral symptoms: disinhibition, apathy or inertia, loss of empathy; perseverative or ritualistic behavior, or hyper-focus on oral functions and dietary changes.
Individuals with frontotemporal dementia with a language variant often have progressive aphasia. Diagnosis of a language variant requires a significant decrease in language ability, as evidenced by the amount of speech production and deficits in the selection of accurate words, grammar, or comprehension. The learning memory and perceptual motor cognitive domains are retained for a longer time. Frontotemporal dementia is probable if genetic testing or family history is positive or if neuroimaging identifies frontal and temporal atrophy. Extrapyramidal symptoms, muscle atrophy or weakness, and visual hallucinations may sometimes be present (APA, 2013).
Approximately 5% of dementia is frontotemporal. The mean duration of survival is 6 to 11 years after symptoms start and 3 to 4 years after a diagnosis is made. Frontotemporal dementia often occurs when an individual is in their early 60s and may result in legal, work, and family problems due to disruptive, disinhibited behavior (APA, 2013).
Major Neurocognitive Disorder Due to HIV Infection
HIV dementia is diagnosed when individuals have cognitive impairment and HIV infection with no other medical or psychiatric condition that better explains their cognitive decline. Primary features include problematic complex attention and executive function. Emotional lability, aggression, and apathy may also be present. The course of HIV dementia is often variable and may include improvement, progression, or fluctuations. Less than 5% of individuals with HIV experience major neurocognitive disorders due to HIV infection (APA, 2013).
Major Neurocognitive Disorder Due to Huntington’s Disease
Insidious onset and progressive cognitive impairment are inherent components of Huntington’s disease. Executive functioning declines early in the course of Huntington’s disease, and learning and memory are preserved for a longer time. Cognitive and behavioral changes precede the slowing of voluntary movement and choreiform movements that are characteristic of Huntington’s disease. Diagnosis is based on the presence of these extrapyramidal motor abnormalities and a family history of Huntington’s disease or genetic testing. Associated symptoms include apathy, anxiety, depression, irritability, obsessive-compulsive behaviors, disinhibition, and impulsivity. The average age of diagnosis is 40 years, with progressive deterioration and death approximately 15 years after diagnosis. In the late-stage Huntington’s disease, motor impairment and inability to swallow become profound (APA, 2013).
Major Neurocognitive Disorder Due to Lewy Body Disease
Insidious onset and gradual progression characterize Lewy body dementia. Individuals with Lewy body dementia may display two or more of the following symptoms: 1) fluctuating cognition, attention, and alertness; 2) recurrent detailed visual hallucinations; and 3) cognitive declines followed by sudden Parkinsonian symptoms, or they may display at least one of these symptoms along with either rapid eye movement, sleep disorder, or severe neuroleptic sensitivity, including neuroleptic malignant syndrome (altered mental status, fever, and muscle rigidity). Typically, complex attention and executive function decline are early symptoms, and sudden Parkinsonian symptoms develop at least a year later. Behavioral disturbances, auditory hallucinations, delusions, depression, repeated falls, unexplained loss of consciousness, and orthostatic hypotension may also be present. Although potentially helpful in treating hallucinations and other psychotic symptoms, antipsychotic medications with neuroleptic components should be avoided in individuals with Lewy body dementia (APA, 2013; Hershe & Coleman-Jackson, 2019).
Approximately 2% to 30% of dementia are thought to be Lewy body dementia. The male-to-female ratio for Lewy body dementia is 1.5 to 1. The mean duration of survival is 5 to 7 years. Lewy body dementia may occur after the age of 60 but most commonly develops in the mid-70s, with a median age of 76.3 years. Quality of life tends to be extremely low in large part because of visual hallucinations, motor impairment, and sleep problems. Individuals with Alzheimer’s and vascular dementia often also have concurrent Lewy body pathology, which explains the variability in presentation and clinical course (APA, 2013; Hershe & Coleman-Jackson, 2019).
Major Neurocognitive Disorder Due to Parkinson’s Disease
Up to 75% of individuals who have been diagnosed with Parkinson’s disease will experience an insidious onset and gradually progressing cognitive impairment. Associated symptoms include apathy, depression, anxiety, hallucinations, delusions, personality change, rapid eye movement, sleep disorder, and sleepiness during the day. Parkison’s disease occurs more frequently in men than in women and most commonly presents when a person is in their early 60s. Parkinson’s dementia may co-occur with Alzheimer’s disease and vascular dementia (APA, 2013).
Major Neurocognitive Disorder Due to Prion Disease
An insidious onset characterizes prion disease, rapid progression; biomarker evidence of prion disease or symptoms of prion disease, such as myoclonus or ataxia; and dementia that is not better explained by another medical or psychiatric condition. Prion disease is associated with a group of sub-acute spongiform encephalopathies, with Creutzfeldt-Jacob disease as the most common. Symptoms include cognitive impairment, ataxia, chorea, myoclonus, dystonia, and an increased startle reflex. Magnetic resonance imaging shows multifocal gray matter hyperintensities in cortical and subcortical brain regions (APA, 2013).
The peak age of developing prion disease is 67 years. Prodromal symptoms, such as fatigue, anxiety, appetite issues, sleeping issues, and decreased concentration, may precede altered vision, incoordination, abnormal movements, and rapidly progressing dementia. Typically, severe symptoms that interfere with daily functioning and quality of life develop over 3 to 6 months (APA, 2013).
Major Neurocognitive Disorder Due to Vascular Disease
Vascular dementia is characterized by an insidious onset, gradual progression, and cerebrovascular disease or decline in the cognitive domains of complex attention and executive function. Vascular dementia is probable if neuroimaging shows parenchymal injury associated with cerebrovascular disease, symptoms are associated with cerebrovascular events, or clinical and genetic evidence supports the presence of cerebrovascular disease. Vascular lesions may occur in tiny or large vessels and may be localized or diffuse. A stair-step presentation, with cognitive declines and plateaus, may mirror the occurrence of cerebrovascular events. Abulia (lack of initiative), depression, emotional lability, and psychomotor slowing may also be present (APA, 2013).
Vascular dementia is the second most common type of dementia after Alzheimer’s disease. Approximately 16% of people 80 years and above have vascular dementia, and within three months after experiencing a stroke, 20% to 30% of individuals are diagnosed with vascular dementia. Vascular dementia and Alzheimer’s disease frequently occur together (APA, 2013).