Chapter 20: spectrum frontotemporal dementia Flashcards
Types of spectrum frontotemporal dementia
- Behavioral variant (bvFTD): most common variant.
- Primary progressive aphasia (PPA): language variant.
- Amyotropic lateral sclerois (ALS)
- Corticobasal syndrome (CBS)
- Progressive subpranuclear palsy (PSP)
These are all characterized by either a change in behaviour, language or motor function. Diagnosis takes more than 6 years from the first symptom.
ALS (amyotropic lateral sclerosis)
Is caused by the denervation of the spinal cord, brainstem and motor cortex. This results in spasms, small involuntary muscle contractions (fasciculations) and muscle weakness as a result of loss of muscle bul (atrophy). People develop cognitive impairments and the disease progresses rapidly.
bvFTD (behavioural variant)
The most presenting symptoms are disinhibition, apathy and changes in eating behaviour and diet. Then there are a lot of perservative, stereotype or compulsive behaviours (like hand clapping, lip smacking, repating phrases). The disorder affects executive functions and social cognition, while memory and visuospatial abilities are relatively spared.
In the brain: the prefrontal cortex, the orbitofrontal cortex, the anterior cingulate cortex, the anterior insula and the subcortical-limbic structures are involved.
PPA (primary progressive aphasia)
Language problems are the most prominent complaint that impair daily living. The problems have a gradual onset and progression. It can cause people to develop visual agnosia and their loss of semantic knowledge can effect their touch, smell and taste. The patients are usually aware of their illness, which causes a disease burden and mood an anxiety problems.
In the brain: the atrophy is more left-sided.
svPPA (semantic variant)
Patients have fluid and grammatically correct speech, but it becomes more ‘empty’. They have word-finding problems and naming problems (anomia). Patients can replace lower-frequency words by higher-frequency words with a similar meaning (like dog instead of hippopotamus). They also lose the ability to understand the meaning of words or develop dyslexia of dysgraphia: reading or writing words irregular as if they are regular (island becomes is-land). They can also develop obsessive-compulsive behavior, disinhibition, irratabilty, food taste changes and impairments in social cognition.
In the brain: a left anterior inferior temporal lobe.
nfvPPA (non-fluent variant)
Patients have a slow, slurred and effortful speech that can be accompanied by errors in speech sound. Their speech rhythm, pitch and prosody decline with disease progression, just like the ability to make and understand longer and gramatically complex sentences. They can have impairment in their phonological loop, memory, executive functions and visuoconstruction.
In the brain: in the left inferior forntal gyrus, insular cortex and the premotor and supplementary motor areas.
lvPPA (logopenic variant)
Non-fluent speech as a result of problems in word-finding. They are different from nfvPPA because they cannot repeat longer words or sentences.
In the brain: atrophy in the posterior temporal and parietal areas.
Misdiagnosis of FTD
Due to the large variation of symptoms between patients, the gradual onset, the young onset and the clinical overlap with other forms of dementia causes the disease to often be misdiagnosed. This form of dementia is part hereditary. FTD can have a lot of symptoms in common with autism, so the disease can be mistaken for that.
FTD in the brain
FTD is characterized by a strongly assymmetric pattern of atrophy of the frontal and temporal lobes, while people with Alzheimer’s show a more symmetrical pattern.
Screening FTD
- Clinical Dementia Rating Scale (CDRC)
- The Montreal Cognitive Assessment (MCA)
Symptoms of FTD
- Disturbed social perception
- Disturbed automatic attribution
- Impaired understanding and interpretation of social information
- Impaired regulation of social behaviour
