Neurology · Dementia
The facts most likely to be tested
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Frontotemporal dementia typically presents with early personality changes, disinhibition, and socially inappropriate behavior rather than memory loss.
The behavioral variant is the most common subtype, characterized by apathy, hyperorality, and compulsive behaviors.
Primary progressive aphasia is a distinct clinical presentation involving the progressive decline of language production or word comprehension.
Neuroimaging via MRI reveals focal atrophy of the frontal and temporal lobes, often described as knife-edge atrophy.
Histopathology frequently demonstrates Pick bodies, which are spherical tau-protein inclusions within neurons.
Frontotemporal dementia is distinguished from Alzheimer disease by the relative preservation of visuospatial skills and episodic memory in the early stages.
Management is primarily supportive and symptomatic, as there are no disease-modifying therapies, and cholinesterase inhibitors are generally ineffective.
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A 58-year-old man is brought to the clinic by his wife due to progressive behavioral changes over the past 18 months. She reports that he has become increasingly impulsive, recently making several inappropriate sexual comments to neighbors and shop clerks. He has also developed a new habit of eating excessive amounts of sweets and has become apathetic toward his family. On examination, he is disinhibited but scores 28/30 on the Mini-Mental State Examination, with preserved memory and visuospatial orientation.
What is the most likely diagnosis?
Frontotemporal dementia
The patient's presentation of early personality changes, disinhibition, and hyperorality with preserved memory is classic for the behavioral variant of frontotemporal dementia, testing the distinction from Alzheimer disease.
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Etiology / Epidemiology
Common cause of early-onset dementia (age 45-65). Characterized by focal atrophy of frontal and temporal lobes.
Clinical Manifestations
Presents with personality changes and disinhibition. Language variants include primary progressive aphasia.
Diagnosis
Diagnosis is clinical; MRI brain shows focal atrophy. Pick bodies are the classic histopathologic finding.
Treatment
No disease-modifying therapy. SSRIs are first-line for behavioral symptoms. Avoid antipsychotics.
Prognosis
Rapidly progressive with a mean survival of 6-8 years. Death usually results from aspiration pneumonia.
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Epidemiology & Etiology
Frontotemporal dementia (FTD) is one of the most common causes of early-onset (<65) dementia, rivaling Alzheimer's in patients under 60. It typically presents in patients aged 45-65 years. A strong genetic component exists, with up to 40% of cases showing a family history of dementia.
Pertinent Anatomy
Atrophy is localized to the frontal and temporal lobes. This specific localization explains the early loss of executive function and social cognition compared to the memory-predominant deficits of Alzheimer's.
Pathophysiology
The disease involves the accumulation of abnormal proteins, most commonly tau protein or TDP-43. These inclusions lead to neuronal death and synaptic loss. The presence of Pick bodies—spherical, silver-staining tau inclusions—is the hallmark of the Pick disease variant.
Clinical Manifestations
The behavioral variant is marked by social disinhibition, apathy, and loss of empathy. Patients may exhibit hyperorality and compulsive behaviors. Language variants present as primary progressive aphasia, where speech fluency or word-finding is impaired. Red flags include sudden onset of socially inappropriate behavior or criminal activity in a previously stable adult.
Diagnosis
The MRI brain is the gold standard for identifying focal atrophy in the frontal or temporal regions. Neuropsychological testing is required to document executive dysfunction or language deficits. Exclude metabolic causes like B12 deficiency or hypothyroidism before confirming the diagnosis.
Treatment
Management is purely supportive and symptomatic. SSRIs (e.g., sertraline) are the first-line agents to manage behavioral symptoms and impulsivity. Avoid antipsychotics as they may worsen parkinsonism and increase mortality in patients with dementia.
Prognosis
The disease is rapidly progressive compared to Alzheimer's. Patients typically require institutional care within a few years. Aspiration pneumonia and falls are the leading causes of mortality.
Differential Diagnosis
Alzheimer's disease: memory loss is the initial, predominant symptom
Vascular dementia: stepwise decline with focal neurological deficits
Lewy body dementia: visual hallucinations and parkinsonism
Normal pressure hydrocephalus: wet, wobbly, and wacky triad
Depression: pseudodementia with preserved cognitive testing