Behavioral variant frontotemporal dementia

General

bvFTD involves a progressive disturbance in personality, emotion, and behavior (Ljubenkov and Miller, 2016)

• reflects decline in function / connectivity among several paralimbic brain regions, including medial frontal, orbitofrontal, ACC, and frontal insular cortices (Ljubenkov and Miller, 2016)
• symptoms driven by severity of dysfunction in nondominant frontotemporal regions (generally right-sided)
• apathy is most common first symptom (passivity, indecisiveness, loss of interest (in hygiene, hobbies, social interaction, work responsibilities, domestic responsibilities) (Ljubenkov and Miller, 2016)
• social disinhibition or loss of tact is typically experienced by a profound and obvious loss of insight. (Ljubenkov and Miller, 2016)
• though not a core criteria, psychotic phenomenon such as hallucinations and bizarre or somatic delusions early in the dementia course can be associated with C9ORF72 mutation (Finger 2016)

Diagnosis

Clinical criteria for bvFTD (Rascovsky) 97

1) Shows progressive deterioration of behavior and/or cognition by observation or history

2) For possible diagnosis, three of the following must be present to meet criteria

a. Early behavioral disinhibition (1+ of the following):

i. Socially inappropriate behavior

ii. Loss of manners or decorum

iii. Impulsive, rash, or careless actions (including inappropriate disclosure of information to strangers, like medical information or finances 95)

b. Early apathy or inertia (1+ of the following):

i. Apathy (may spend hours sitting on the couch staring at wall or television 95)

ii. Inertia

c. Early loss of sympathy or empathy (1+ of the following):

i. Diminished response to other people’s needs and feelings

ii. Diminished social interest, interrelatedness, or personal warmth

d. Early perseverative, stereotyped, or compulsive/ritualistic behavior (1+ of the following):

i. Simple repetitive movements

ii. Complex, compulsive, or ritualistic behaviors

iii. Stereotypy of speech

e. Hyperorality and dietary changes (1+ of the following):

i. Altered food preferences (typically sweets 95)

ii. Binge eating, increased consumption of alcohol or cigarettes

iii. Oral exploration or consumption of inedible objects

f. On neuropsychological testing, all the following symptoms:

i. Deficits in executive tasks

ii. Relative sparing of episodic memory

iii. Relative sparing of visuospatial skills

3) For probable diagnosis, all the following symptoms must be present:

a. Meets criteria for possible bvFTD

b. Exhibits significant functional decline (by caregiver report, CDRS, or FAQ)

c. Imaging results consistent with bvFTD (1+ of the following):

i. Frontal and/or anterior temporal atrophy on MRI or CT

ii. Frontal and/or anterior temporal hypoperfusion or hypometabolism on SPECT or PET

4) For bvFTD with definite FTLD pathology:

a. Must meet criteria for possible or probable bvFTD

b. Must have either of the following:

i. Histopathological evidence of FTLD on biopsy or at post-mortem

ii. Presence of a known pathogenic mutation

5) Exclusionary criteria for bvFTD, criteria A and B must be answered negative for any bvFTD diagnosis, criterion C can be positive for possible but not probable bvFTD

a. Pattern of deficits is better accounted for by other non-degenerative nervous system or medical disorders

b. Behavioral disturbance is better accounted for by a psychiatric diagnosis

c. Biomarkers strongly indicative of Alzheimer’s disease or other neurodegenerative process

References

Finger, E. C. Frontotemporal Dementias. Contin. Minneap. Minn 22, 464–489 (2016). https://pubmed.ncbi.nlm.nih.gov/27042904/

Ljubenkov, P. A. & Miller, B. L. A Clinical Guide to Frontotemporal Dementias. FOCUS 14, 448–464 (2016). https://pubmed.ncbi.nlm.nih.gov/31975825/