In plain English
Behavioural Variant Frontotemporal Dementia (bvFTD) is the most common Frontotemporal Dementia syndrome. It typically begins in the fifties or sixties with gradual change in personality, judgment and social conduct, with relatively preserved memory in the early stages.
What bvFTD is
Behavioural Variant Frontotemporal Dementia is a neurodegenerative disease primarily affecting the frontal and anterior temporal lobes. The cardinal feature is a gradual change in personality and behaviour, rather than memory loss. Onset is most commonly between 50 and 65, although later cases occur. bvFTD accounts for around 60 per cent of Frontotemporal Dementia cases.
The diagnostic features
The 2011 International FTD Consortium criteria (Rascovsky et al.) require three of the following six features to be present, with progressive decline and functional impact:
- Disinhibition: socially inappropriate behaviour, impulsive purchases, loss of social manners, criminal behaviour;
- Apathy or inertia: loss of motivation, withdrawal from previously enjoyed activities;
- Loss of sympathy or empathy: reduced concern for others, emotional flatness;
- Perseverative, stereotyped or compulsive behaviour: repetitive routines, hoarding, ritualised speech or actions;
- Hyperorality and dietary change: sweet preference, overeating, putting non-food items in the mouth;
- Neuropsychological profile: executive dysfunction with relative sparing of memory and visuospatial skill.
How it differs from Alzheimer's Disease
Several features help distinguish bvFTD from Alzheimer's Disease:
- Memory relatively preserved early in bvFTD;
- Personality change comes before, not after, cognitive change;
- Family notice the change far more than the person themselves;
- Insight is often markedly reduced from the outset;
- Imaging shows frontal or anterior temporal atrophy, not medial temporal.
How it is diagnosed
Diagnosis rests on a careful history (especially from family) plus:
- Addenbrooke's Cognitive Examination: fluency is often markedly reduced, while memory may be preserved;
- Magnetic Resonance Imaging: frontal or asymmetric anterior temporal atrophy; may be normal in early disease;
- FDG-PET or perfusion SPECT where Magnetic Resonance Imaging is inconclusive (NICE NG97 1.2.23);
- Neuropsychometric assessment showing executive and social cognition deficits with preserved memory;
- Genetic testing where there is a strong family history (C9orf72, MAPT, GRN being the commonest gene defects).
Treatment
No licensed medication slows or reverses bvFTD. Symptomatic and supportive treatment includes:
- Selective Serotonin Reuptake Inhibitors (Sertraline, Citalopram, Mirtazapine) for behavioural symptoms: disinhibition, compulsive behaviour, irritability, overeating;
- Trazodone for sleep disturbance and agitation;
- Atypical antipsychotics, rarely and cautiously, for severe agitation;
- Cholinesterase Inhibitors are NOT recommended; they may worsen behaviour;
- Structured routine, occupation, environmental modification, carer education.
Motor Neuron Disease overlap
Approximately 15 per cent of people with bvFTD develop features of Motor Neuron Disease (Amyotrophic Lateral Sclerosis), with limb weakness, muscle wasting, fasciculation or bulbar (swallowing/speech) symptoms. This combination has a more rapid course. Any new motor symptoms warrant neurology assessment.
Practical and family considerations
bvFTD presents distinct challenges for families:
- The personality change is often felt as a loss of the person who was, in addition to a physical illness;
- Behaviours may be embarrassing, frightening or financially harmful;
- Insight is reduced, making conversation about the condition difficult;
- The person may resist help, even when clearly needed.
Specialist support from Frontotemporal Dementia Support and Rare Dementia Support is highly recommended. Early Lasting Power of Attorney is essential; capacity may be lost earlier than in other dementias.
Where The Dementia Service fits in
bvFTD is often missed in initial assessments because memory may be preserved and the cognitive test score may be relatively normal. The Dementia Service can provide structured assessment and onward FDG-PET arrangement where suspicion is high, with the structured letter going to your GP.
Frequently asked questions
Why does the person not realise something is wrong?
Reduced insight is a core feature of bvFTD. The frontal lobes that underpin self-monitoring are affected by the disease. Family typically notice the change far earlier than the person themselves.
Are Cholinesterase Inhibitors helpful in bvFTD?
No. Cholinesterase Inhibitors are not recommended for Frontotemporal Dementia and may worsen behavioural symptoms. SSRIs are the usual first-line for behavioural management.
Is bvFTD inherited?
About 10 to 30 per cent of bvFTD cases have a strong family history. C9orf72, GRN and MAPT are the commonest genes involved. Genetic counselling is recommended where there is a clear family history.
What is the relationship between bvFTD and Motor Neuron Disease?
About 15 per cent of people with bvFTD develop features of Motor Neuron Disease. The C9orf72 gene mutation is the most common shared cause. Any new motor symptoms warrant neurology assessment.
How is bvFTD different from a personality disorder?
bvFTD is a progressive neurodegenerative disease beginning in adulthood. Personality disorders are typically present from young adulthood and do not show progressive cognitive decline or frontal atrophy on imaging.
References
- Rascovsky K et al. Sensitivity of revised diagnostic criteria for the Behavioural Variant of Frontotemporal Dementia. Brain 2011.
- NICE NG97: Dementia, assessment, management and support.
- Boeve BF et al. Frontotemporal Dementia and parkinsonism. Lancet Neurol 2022.
- Rare Dementia Support. https://www.raredementiasupport.org