Cognitive Definitions
Normal aging (AACD age associated cognitive decline): The normal aging process is associated with declines in certain cognitive abilities as below but not others.
Declines with age - Attention: ability to focus, concentrate & ignore irrelevant information
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Executive function: ability to plan & organize goal directed behavior
Decreased ability to plan, organize & multitask
Processing speed: slower thinking, slow to respond
Working memory: difficulty holding information in mind
Visual spatial abilities
Problem solving
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Long term Memory:
Explicit /Declarative memory (conscious memory for events, facts, experiences): declines throughout life. Includes episodic memory (stores personal experiences) and semantic memory (stores facts)
Implicit/Nondeclarative memory (unconscious memory for motor & cognitive skills): does not decrease with age. Includes procedural memory (memory for skills, e.g. ride a bike, eat).
Language: decreased word retrieval with age
All these can cause decrements in the cognitive abilities needed for driving - e.g. visual attention/processing (the ability to select visual stimuli based on spatial location), visual perception (the ability to accurately perceive and interpret what is seen), executive function, and memory.
Any baseline deficits worsen with age (ex ADHD, autism, learning disabilities)
Decreased hippocampal, frontal and temporal lobe volumes.
Does not decline with age
Verbal abilities: Often vocabulary, reading & verbal reasoning are unchanged or improve with age. An exception is word retrieval.
Implicit/nondeclarative procedural memory
Cognitive reserve: Higher levels of education, participation in mental activities and baseline intelligence allow some individuals to better withstand pathologic changes to the brain.
Mild cognitive impairment (MCI): Cognitive impairment more than expected for age and educational level but that does not affect functioning.
Epidemiology: 20% of people >65 (1). Progression to dementia is ~12% a year, 3x risk (1-4% a year in average elderly), 60% in 10 years (2). Approximately 50 % of MCI patients progress to AD within 3 years.
Non-amnestic MCI: in domains other than memory
Amnestic MCI: memory loss, Conversion rate is higher with amnestic MCI >60% in 2 year 3
No treatment is available for MCI
Dementia: Cognitive impairment in at least 2 cognitive domains that is more than expected for age and educational level and effect functioning
Mild dementia: Independent of basic ADL’s (dressing, bathing) but may need help with some independent ADL’s. Able to live independently.
Moderate dementia: Unable to do most independent ADL’s and may need help with basic ADL’s. They may start to have behavioral & personality changes. Need Some supervision.
Severe dementia: Needs significant help with basic ADL’s. long term memory becomes impaired. Require 24 hr. supervision.
Differential of dementia
Depression
Problems with attention, focusing and concentrating, apathy and psychomotor slowing
Often say I don’t know on cognitive test questions
Neuropsychological testing often shows executive dysfunction, poor attention. Preserved memory and language
Sleep deprivation/Sleep apnea - causes psychomotor slowing, memory/word retrieval difficulties, poor attention, concentration and focusing, executive dysfunction
Attention-deficit/hyperactivity disorder (ADHD) - 8% of children and 4.4% of adults (4). Often confused with dementia and MCI, symptoms often worsen with age.
Menopause
Approximately 2/3 of women complain of memory loss and/or "brain fog" during menopause (5).
Other common symptoms - difficulties with focusing, organizing, concentration, recalling names, and paying attention.
Peri and post-menopausal woman perform more poorly on standardized neuropsychological tests, in the areas of verbal memory, working memory, attention, executive function, and processing speed.
Cognitive symptoms usually improve over time
Hormone replacement therapy - some studies have concluded that estrogen replacement therapy improves cognition and helps prevent dementia, but others suggest it has no effect or even a negative effect on cognitive faculties. Discrepancy likely related to different types of estrogen and varying timing of use.
Primary age related Tauopathy (PART, discovered by MSSM neuropathologist Dr. John Crary) - Alzheimer neurofibrillary tangles (NFT) (tau pathology) without Amyloid beta accumulation usually in medial temporal lobe. Often seen in the brains of normal elderly.
Patients can be cognitively normal, mildly cognitively impaired, or with amnestic dementia. Rarely with profound impairment
Unclear if it is a unique entity or part of AD spectrum
Hearing loss
Metabolic/Autoimmune/Infectious Causes