Cognitive Impairment

Definitions, Description and Evaluation➢Neurocognitive disorders – conditions in which an acquiredimpairment of cognitive functions occurs

➢ Decrease in function involving at least one of the followingneuropsychological domains (memory/learning, complex attention,executive function, perceptual or motor abilities, language or socialcognition)

➢Dementia – characterized by a gradualand progressive decline in previouslyacquired cognitive function => impairedsocial or occupational functioning, withloss of independence

➢Diagnosis of dementia – impairment of at least two of previouslyneuropsychological domains

➢Incidence of dementia increases with age – is not an inevitable consequenceof normal aging

➢Subtle cognitive decline with normal aging- common but not universal andshould not affect independence in daily functioning

Definitions, Description and Evaluation

➢Age-associated cognitive decline – most notable for some slowing ofprocessing speed and reaction time

➢Learning/acquisition of new information decreases with age, but delayed recall remains intact

➢Language comprehension and vocabulary (semantic memory) – preserved in normal aging

Definitions, Description and Evaluation

Mild Cognitive Impairment (MCI)➢MCI – intermediate stage between normal aging and dementia

➢Diagnosis of MCI – clinical judgment and the following fourfeatures:

➢Subjective reports (from the patient or reliable informant) of problems with memories

➢Objective impairment on cognitive testing in one or more cognitive domains

➢Diminished independence in daily function

➢No significant impairment in occupational or social functioning

➢The presence of significant functional deficit –distinguishes dementia from MCI

➢MCI can be anamnestic MCI or nonanamnesticMCI – presence or absence of memory deficitsand the number of cognitive domains that areaffected

➢Patients with MCI – significantly increasedconversion to dementia (10% – 15% per year)

➢Cognitively normal age-matched controls –develop dementia (1%-2% per year)

➢Within 6 years from diagnosis – 80% of patientswill progress to dementia

Mild Cognitive Impairment (MCI)

➢No treatments or interventions can delay the onset of Alzheimerdisease or other types of dementia in patients with MCI

➢Most patients with amnestic MCI have pathologic findings ofAlzheimer disease

➢Degenerative pathologies (Lewy body disease) and nondegenerativepathologies (vascular disease) – cause of MCI

Mild Cognitive Impairment (MCI)

➢MCI associated with underlying Lewy bodydisease – diminished executive functioning,impairment of visuospatial abilities or both

➢MCI due to vascular disease – cognitiveprofile of impaired executive function orprocessing speed, with spared verbalmemory

➢Other nondegenerative, potentiallyreversible, diseases cause of MCI :hypothyroidism, vitamin B12 deficiency,depression

Mild Cognitive Impairment (MCI)

Dementia

➢ Progressive deterioration of cognitive functionsevere enough to impair occupational or socialfunctioning

➢ 35 million persons live with dementiaworldwide – number is expected to triple by2050 as life expectancy increase

➢ Alzheimer disease – most common type ofdementia (60%-80%)

➢ Advancing age – major risk factor for dementia

➢ For every 5 years > age 65 years – prevalenceof Alzheimer disease doubles

➢Vascular risk factors for MCI and dementia: cardiac disease, diabetesmellitus, hypertension, obesity, tobacco use

➢Additional risk factors for Alzheimer disease: APOE ε4 allele, historyof head injury, mid- and late-life depression

➢Higher educational, occupational advancement – associated withdecreased risk or delayed onset of dementia

Dementia

➢Median survival time from age of onset of dementia – 3 to 12 years,with longer durations associated with earlier age of onset

➢Persons with Alzheimer disease and dementia with Lewy bodies –survive an average of 8 years

➢Persons with frontotemporal dementia – survive an average of 6 years

➢Persons with dementia

associated with underlying

vascular disease – survive an

average of 4 years

Dementia

Evaluation of the Patient with Suspected Cognitive Impairment

➢Following situations should prompt testing for dementia/cognitive impairment inpersons ≥ 65 years:

➢Patients with cognitive symptoms, with or without functional impairment

➢Patients who routinely miss scheduled appointments or arrive on the wrongdate or at the wrong time

➢Patients with inability toaccurately follow instructions

➢Patients with unexplained weightloss or failure to thrive

➢Patients with new onset or worsening depression or anxiety,with or without cognitive symptoms

➢Report from a witness, confirmed or unconfirmed by thepatient, of a change in cognition, poor or decreasedjudgment, loss of initiative, or changes in behavior

➢Patients with known risk factors for cognitive impairment(such as HIV infection or a personal history of alcohol abuse)

Evaluation of the Patient with Suspected Cognitive Impairment

➢A careful history should focus on:➢ Evolution of symptoms

➢ Rate of progression

➢ Functional impact on activities of daily living and work performance

➢Patients with even mild restrictions – increased risk of progressing todementia

➢Vascular risk factors – should be identified

➢Information on medication use and substance abuse – elicited

➢Screening for depression – imperative

Evaluation of the Patient with Suspected Cognitive

Impairment

➢Late-life depression – prodromal Alzheimer disease

➢Depression – risk factor for future development of cognitive impairment,dementia and Alzheimer disease (ratio of 1.85 for all cause of dementia)

➢Cerebrovascular disease – precipitate late-life depression

Evaluation of the Patient with Suspected Cognitive Impairment

➢Detailed family history:➢ History of cognitive impairment➢ Dementia➢ Significant psychiatric illness in later life➢ Motoneuron disease➢ Parkinsonism

➢ Screening tests – cognitive impairment in patients who report cognitivedifficulties

➢ Performance on these tests – serve as baseline and are used to monitordisease progression

The presence suggests afamilialneurodegenerativedisease

Evaluation of the Patient with Suspected Cognitive Impairment

➢Mini-Mental State Examination: score < 23 dementia –most extensively studied screening instrument

➢This instrument has several weaknesses:▪ Lack of sensitivity in identifying early signs of dementia

▪Absence of tasks that test executive function

➢Montreal Cognitive Assessment and “Mini-Cog” test –screen for impairments of executive function

➢Self-Administered Gerocognitive Examination and TestYour Memory – detect mild cognitive impairment and earlydementia

Evaluation of the Patient with Suspected Cognitive Impairment

➢Detailed neuropsychological testing – useful for the following patients:

➢Those with milder cognitive symptoms – determine if cognitive difficulties are withinthe realm of normal age-associated cognitive decline vs. MCI

➢Definite dementia – diagnosed on the basis of clinical impression and results ofscreening cognitive tests – have clinical features overlapping two or more underlyingpathologic processes

➢Those with cognitive symptoms whose clinical picture is confounded by significantdepression

➢Impaired performance on neuropsychological testing is determined bea patient’s performance compared with healthy age- and education-matched controls

➢Without premorbid results, this testing can only estimate the patient’spremorbid baseline to determine cognitive areas of presumed decline

➢It can serve as a baseline with which to compare future test results

➢To identify reversible causes of cognitive decline –laboratory tests:➢Complete blood count

➢Liver chemistry studies

➢Thyroid function tests

➢Serum electrolyte

➢Blood urea nitrogen

➢Creatinine

➢Vitamin B12

➢A syphilis screening test – in high risk population

➢Evaluating for autoimmune disease – relevant symptoms arepresent

➢In at-risk populations – HIV serologies

➢Once dementia confirmed – structural neuroimaging study (MRIor CT scan) to evaluate for nondegenerative causes

➢MRI is more sensitive for: inflammation, infection, acute stroke,tumor, posterior fossa lesion, characteristic imaging findings ofCreutzfeldt-Jakob disease

➢Cerebrospinal fluid analysis – in the following clinical situations:➢Rapidly progressive dementia

➢Age of onset < 60 years

➢Malignancy or paraneoplastic disorders

➢Suspicion of acute or subacute infection or of an immuno-suppressed orimmunodeficient state

➢Positive syphilis or Lyme serology

➢Systemic autoimmune disease or suspected CNS inflamatory-disorder

➢Brain MRI, cerebrospinal fluid (CSF) analysis, serologic tests andelectroencephalography – early-onset or rapidly progressive cognitive decline

➢Creutzfeldt-Jakob disease – most common cause of rapidly progressivedementia; disease duration < one year until death

Vascular Neurocognitive Disorder (VND)

➢Describes cognitive impairment of any degree due tocerebrovascular disease

➢Second most common cause of cognitive impairment in olderpersons

➢Cerebrovascular syndromes associated with cognitive decline:➢Multiple cortical infarcts, multiple subcortical infarcts, silent infarcts,

some combination of these

➢Single infarcts (lacunar infarcts) in: thalamus, basal ganglia – vitalinterconnections with multiple cortical regions

➢Subcortical ischemic small-vessel disease with white matter lesions

➢Cerebrovascular syndromes associated with cognitive decline:

➢Hemorrhage: intraparenchymal hemorrhage, subarachnoid hemorrhage, subduralhematoma

➢Hypotensive episodes – border-zone infarcts

➢Cerebral vasculitis

➢Diagnosis is made – neuroimaging or clinical history => evidenceof a stroke or subclinical cerebrovascular disease – responsiblefor impairment of at least one cognitive domain

➢Onset – acute or insidious, progression – stepwise or gradual

➢Noncognitive symptoms: focal neurologic findings, depression,pseudobulbar palsy, gait abnormalities, urinary difficulties

➢Impairments of attention, executive function, processing speed –commonly seen on neuropsychological testing, especially in patientswith a subcortical vascular syndrome

➢Memory impairment – less prominent

➢Treatment – aimed at identifying and treating cerebrovascular risk factors(smoking, diabetes mellitus, hyperlipidemia, hypertension, ischemic heartdisease, atrial fibrillation, hypercoagulable states) and at lowering stroke risk(antiplatelet or anticoagulant therapy)