A 58-year-old man is brought by his wife with a 2-year history of progressive behavioral changes. He has become increasingly disinhibited, making inappropriate comments at social gatherings and engaging in compulsive eating of sweets despite being diabetic. His wife reports he no longer shows concern about his appearance or family responsibilities. Neurological examination reveals mild pyramidal signs in the lower limbs. MRI brain shows prominent frontal and anterior temporal lobe atrophy. Mini-Cog is 2/3, but he performs well on visuospatial tasks. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Behavioral Variant Frontotemporal Dementia (bvFTD) ### Key Diagnostic Features **Key Point:** Behavioral variant FTD is characterized by prominent early behavioral and personality changes with relative preservation of memory and visuospatial function in early stages. ### Clinical Presentation in This Case | Feature | Finding | Significance | |---------|---------|---------------| | **Behavioral changes** | Disinhibition, inappropriate comments, compulsive eating | Early and prominent | | **Personality** | Loss of concern for appearance and family | Apathy and loss of social awareness | | **Cognition** | Preserved visuospatial skills, poor Mini-Cog | Memory relatively spared early | | **Motor signs** | Mild pyramidal signs | ALS overlap possible (ALS-FTD spectrum) | | **Neuroimaging** | Frontal and anterior temporal atrophy | Pathognomonic for bvFTD | ### Diagnostic Criteria for bvFTD **High-Yield:** The revised criteria (Rascovsky et al., 2011) require early behavioral disinhibition OR apathy/inertia, plus neuroimaging evidence of frontal/temporal atrophy or hypoperfusion. 1. **Early behavioral change** — disinhibition, apathy, loss of empathy, or compulsive behavior 2. **Relative sparing of memory and visuospatial function** — distinguishes from Alzheimer disease 3. **Frontal/anterior temporal atrophy** on MRI or hypoperfusion on PET 4. **Preserved insight initially** — may be lost later ### Pathophysiology **Key Point:** bvFTD is associated with tau or TDP-43 pathology, with tau-positive cases (Pick disease) showing more severe behavioral changes and faster progression. ### Differential Features | Disorder | Memory | Visuospatial | Behavior | Imaging | |----------|--------|--------------|----------|----------| | **bvFTD** | Preserved early | Preserved early | Prominent early | Frontal/temporal atrophy | | **Lewy body dementia** | Early impairment | Early impairment | Behavioral changes late | Generalized atrophy | | **Alzheimer disease** | Early impairment | Late impairment | Behavioral changes late | Hippocampal/temporal atrophy | | **Vascular dementia** | Variable | Variable | Variable | Multiple infarcts/white matter | **Clinical Pearl:** The combination of early behavioral disinhibition + preserved visuospatial function + frontal/temporal atrophy is virtually pathognomonic for bvFTD. ### Management Considerations - SSRIs may help behavioral symptoms (e.g., sertraline, paroxetine) - Avoid antipsychotics if possible — increased mortality risk - Screen for ALS (EMG) given pyramidal signs - Genetic counseling if family history present (C9orf72, GRN, MAPT mutations) **Mnemonic — bvFTD RED FLAGS:** **R**estless, **E**ating compulsions, **D**isinhibition, **F**rontal atrophy, **L**oss of empathy, **A**pathy, **G**enetic (familial), **S**ocial withdrawal.