Frontotemporal and Lewy Body Dementias: Symptoms and Diagnosis
Frontotemporal Dementia
Primary Progressive Aphasia
Primary progressive aphasia (Measure 82) is characterized by an insidious alteration of language due to atrophy in the left perisylvian areas, in the absence of dementia. It involves a progressive loss of language that takes at least two years to develop. After these two years, cognitive symptoms appear. There are two types: fluent and nonfluent. It begins as aphasia and then progresses to dementia.
Manifestations
- Increased phonological errors
- Reduced verbal production
- Hesitant speech with a reduction in sentence length
- Decreased verbal agility
- Frequent repetition of words
- Literal and semantic paraphasias
- Neologisms
- Intact repetition (similar to transcortical aphasia)
- Problems in the discrimination of phonemes
Over the years, language deterioration becomes remarkable, sometimes leading to complete silence. In some patients, this occurs around eight years after the onset of symptoms. However, in others, the first two years may involve only language impairment, with cognitive decline appearing later. Language continues to deteriorate, and some patients may become completely nonverbal by the age of eight.
Reading and Writing
Writing gradually deteriorates. Narrative writing is reduced to simple words or sentences that are grammatically incomplete or incorrect in structure. Reading often reveals omissions, substitutions, or additions of words, reflecting the underlying language problems.
Semantic Dementia
Snowden defined semantic dementia in 1989 as “the impairment of semantic memory characterized by an impairment in the understanding of words and in naming, with the presence of fluent speech produced without effort.” It involves semantic memory impairment in the comprehension of words and in naming. The patient speaks fluently but without content. It affects the ability to name objects, understand spoken words, and recognize objects. The mental representation of objects is lost. Patients are aware of their deficits but do not suffer from a lack of understanding.
Lewy Body Dementia
Lewy Body Dementia is more common in individuals under 60. It is multifocal, subcortical, and degenerative. It is characterized by the presence of Lewy bodies and a loss of cognitive abilities, like all dementias. Remember that the definition of dementia requires at least three affected cognitive functions, including memory loss. This loss must be significant enough to interfere with daily activities and occur without impairment of consciousness. There should be an organic etiology, either known or suspected.
Clinical Manifestations
- Failures of episodic memory, evident in spontaneous interaction and specific tests
- Failures in executive function or judgment
- Emotional disorders
- Behavioral disorders: depression, lucid delusions (imagining things while awake)
- Ignorance of what is happening (anosognosia)
- Lack of awareness of the disease, leading to conflicts with family
- Anxiety and depression
- Alterations in appetite, sleep, behavior, and sexual capacity
- Loss of judgment: inability to discern between right and wrong, leading to a breakdown in moral behavior and aggressive acts
- Loss of self-care routines, such as hygiene
When to Suspect Lewy Body Dementia
- History of severe brain injury (e.g., a traumatic brain injury that leads to dementia years later)
- Onset of memory lapses
- Repeated errors and significant behavioral problems
- Vague somatic complaints