Alzheimer's%20disease%20-and-%20dementia Signs and Symptoms
Definition
Dementia
- A clinical syndrome characterized by impairment of multiple higher cognitive functions that include memory, orientation, calculation, language, judgment, executive function, visuo-spatial function and visuo-motor speed
- Usually accompanied or preceded by deterioration in emotional control, social behavior or motivation
- Consciousness is not affected
- May occur in Alzheimer’s disease, cerebrovascular disease and other diseases affecting the brain
- Severity and global nature of cognitive impairment and the accompanying functional disability differentiate it from the relatively mild and variable cognitive decline associated with normal aging
Alzheimer’s Disease (AD)
- Most common cause of dementia
- Majority are sporadic cases which usually present at ≥65 years of age while familial types are rare and present in <65 years (early-onset dementia)
- Short-term memory loss is the most common early symptom
- Other spheres of cognitive impairment manifest after several years
- After memory loss, loss of executive function, language dysfunction, personality and behavioral changes, increasing difficulty with activities of daily living (ADL) and loss of visuo-spatial function are experienced
- Neuropsychiatric symptoms (eg depression, irritability, anxiety, apathy) are common
- Seizures and myoclonus may also manifest late in the disease
Vascular Dementia
- Reported to be the 2nd most common cause of dementia
- Dementia caused by the effects of cerebrovascular disease on cognitive functioning
- May present with an abrupt onset and with stepwise progression
- Suspected in patients with a history of stroke or those with focal neurological signs and symptoms
- Cognitive deficits will depend on what part of the brain is affected by vascular lesions
- May also present subacutely and insidiously with apraxia, progressive decline in gait, attention and planning in the presence of vascular pathology
- Frequently coexists with Alzheimer’s disease (known as mixed dementia), characterized by a gradual progressive dementia occurring in the setting of known cerebrovascular disease
- Young-onset vascular dementia may have a genetic origin
Dementia with Lewy Bodies (DLB)
- Clinically similar to Alzheimer's disease but usually is characterized by earlier Parkinsonian features (eg bradykinesia, rigidity and/or postural instability leading to frequent falls), fluctuating cognition, prominent and recurrent visual hallucinations and tends to have a more rapid evolution
- Onset of cognitive symptoms in relation to motor slowing is ≤1 year
- Important to recognize due to high incidence of life-threatening reactions to antipsychotic medications, particularly the extrapyramidal side effects
Parkinson’s Disease Dementia (PDD)
- Approximately 3 quarters of older patients with Parkinson’s disease develop dementia after 10 years
- Characterized by cognitive and motor slowing, memory impairment and executive dysfunction
- Timing of onset of cognitive symptoms in relation to motor symptoms is >1 year *Please see Parkinson’s Disease and Parkinson’s Disease Dementia disease management chart for more details
Fronto-temporal Dementia
- Also known as frontotemporal lobar degeneration
- Patients usually present at ages 50-60 and represents a significant proportion of people who present with dementia under the age of 65
- In early stages, patients present with changes in personality, deterioration of social skills, emotional blunting, early language disturbance, executive dysfunction and significant apathy
- Memory difficulties, apraxia and other features of dementia usually follow later as the disease progresses
- Course of the disease is usually progressive and tends to be more rapid than Alzheimer's disease
Other Progressive Dementing Disorders
- Huntington’s disease
- Autosomal dominant disease affecting the basal ganglia and other subcortical structures
- Manifests with motor (chorea), mood, behavioral and cognitive symptoms
- Creutzfeldt-Jakob disease
- Rapidly progressive encephalopathy
- Cognitive decline is rapid, usually resulting in death within 1.5 years
Epidemiology
- In 2015, it was found that there was an estimated 50 million people globally that are living with dementia
- Estimated number of people living with dementia in Asia is 22.9 million, in the Americas 9.4 million, in Europe 10.5 million and 4 million in Africa
- In most countries, the age-standardized prevalence of dementia ranges from 5-7%
- In people age ≥60 years old, estimated prevalence of dementia ranges from 4.7% in Central Europe to 8.7% in North Africa and the Middle East
Pathophysiology
- Pathogenesis of Alzheimer’s disease remains unclear but it appears that there is an overproduction and/or decreased clearance of amyloid beta peptides; it also involves a microtubule-associated protein that aids in microtubule assembly
- Neuritic plaques, extracellular deposits of amyloid beta, and neurofibrillary degeneration are the essential neuropathologic changes in Alzheimer’s disease
Etiology
Etiology of Dementia
- Potentially reversible causes
- Infections (eg meningitis and encephalitis)
- Toxic or metabolic encephalopathies (eg hypothyroidism, vitamin B12 deficiency and alcohol-related syndromes)
- Neoplasms
- Hydrocephalus (obstructive or normal-pressure hydrocephalus)
- Delirium
- Depression and other psychiatric conditions
- Drugs that increase anticholinergic burden
- Sensory impairment (eg hearing or vision loss)
- Irreversible causes
- Degenerative diseases (eg Alzheimer’s disease, fronto-temporal dementia and dementia with Lewy body)
- Cerebrovascular disease (eg stroke)
- Genetic disorders (eg Down syndrome)