Cognitive disorders like delirium and major neurocognitive disorder can significantly impact a person's daily life. These conditions affect attention, memory, and other mental functions, leading to challenges in self-care and increased health risks.

Understanding the subtypes and impacts of these disorders is crucial for proper diagnosis and care. From Alzheimer's disease to vascular and frontotemporal disorders, each type has unique characteristics that influence treatment approaches and patient outcomes.

Understanding Delirium and Major Neurocognitive Disorder

Definition of cognitive disorders

• Delirium is an acute, fluctuating disturbance in attention and awareness that develops over a short period (hours to days) and tends to fluctuate in severity throughout the day. It represents a change from baseline attention and awareness and is accompanied by additional disturbances in cognition such as memory deficit, disorientation, language impairment, visuospatial ability decline, or altered perception. Delirium is not better explained by another preexisting, established, or evolving neurocognitive disorder and there is evidence from history, physical examination, or laboratory findings that the disturbance is a direct physiological consequence of another medical condition, substance intoxication or withdrawal, or exposure to a toxin
• Major Neurocognitive Disorder (NCD) is characterized by significant cognitive decline from a previous level of performance in one or more cognitive domains such as complex attention, executive function, learning and memory, language, perceptual-motor skills, or social cognition. These cognitive deficits interfere with independence in everyday activities and do not occur exclusively in the context of a delirium. Additionally, the cognitive deficits are not better explained by another mental disorder such as major depressive disorder or schizophrenia

Subtypes of neurocognitive disorders

• Alzheimer's Disease is characterized by a gradual onset and progressive decline in memory and learning, accompanied by a decline in at least one other cognitive domain such as language, visuospatial ability, or executive function. The onset is insidious and the progression of impairment is gradual. There is an absence of evidence of mixed etiology such as cerebrovascular disease, Lewy body disease, another neurological or systemic disease, or another mental disorder
• Vascular Neurocognitive Disorder presents with clinical features consistent with a vascular etiology, such as the onset of cognitive deficits being temporally related to one or more cerebrovascular events. Evidence for decline is prominent in complex attention and frontal-executive function. There is evidence of the presence of cerebrovascular disease from history, physical examination, and/or neuroimaging, and the deficits are not better explained by another brain disease or systemic disorder
• Frontotemporal Neurocognitive Disorder has an insidious onset and gradual progression, with prominent decline in either language (behavioral variant) or behavior (language variant). There is relative sparing of learning and memory and perceptual-motor function. The behavioral variant is characterized by at least three of the following behavioral symptoms: disinhibition, apathy or inertia, loss of sympathy or empathy, perseverative or compulsive behaviors, hyperorality and dietary changes. The language variant exhibits a prominent decline in language ability, including word-finding difficulties, object naming, dysfluency, and grammatical errors

Impact of cognitive impairments

• Delirium leads to impairment in attention, memory, orientation, language, visuospatial ability, and perception. There is a reduced ability to focus, sustain, or shift attention and a reduced awareness of the environment. This results in impairment in daily functioning and self-care, as well as an increased risk of complications such as falls, pressure ulcers, malnutrition, and dehydration. Delirium is associated with increased morbidity and mortality
• Major Neurocognitive Disorder causes a significant decline in cognitive functioning across domains such as memory, attention, executive function, language, visuospatial ability, and social cognition. This leads to impairment in daily living skills like managing finances, medications, and driving. There is reduced independence and increased reliance on others for care, resulting in a decreased quality of life for both the individual and their caregivers. Major NCD is associated with an increased risk of institutionalization and healthcare utilization

Epidemiology of cognitive disorders

• Delirium has a prevalence of 1-2% in the general population, 14-24% in hospitalized older adults, and up to 80% in critically ill patients. Risk factors for delirium include advanced age, pre-existing cognitive impairment, severe illness, multiple comorbidities, sensory impairment, dehydration, malnutrition, polypharmacy, sleep deprivation, immobility, use of physical restraints, urinary catheterization, pain, and environmental factors such as unfamiliar surroundings and lack of natural light
• The prevalence of Major Neurocognitive Disorder increases with age, affecting approximately 1-2% of individuals aged 65-74, 3-11% of those aged 75-84, and 25-50% of those aged 85 and older. Risk factors include advanced age, family history of NCD (particularly Alzheimer's disease), cardiovascular risk factors (hypertension, diabetes, smoking, obesity), low educational attainment, prior traumatic brain injury, sleep disturbances, lack of physical activity, social isolation, and certain genetic factors such as the APOE ε4 allele for Alzheimer's disease