Apathy: a neurocircuitry model based on frontotemporal dementia.

Area of Science:

• Neuroscience
• Neurology
• Psychiatry

Background:

• Apathy is a common symptom in neurological and psychiatric disorders, yet its neurocircuitry is not fully understood.
• Apathy is a core feature of behavioral variant frontotemporal dementia (bvFTD), characterized by socioaffective and executive dysfunction.

Purpose of the Study:

• To review neuroimaging studies of apathy in frontotemporal dementia (FTD) to refine a neurocircuitry model.
• To inform clinical definitions and diagnostic criteria for apathy in bvFTD.

Main Methods:

• Systematic review of neuroimaging studies investigating apathy in FTD.
• Integration of findings to revise a neurocircuitry model of apathy based on distinct subcomponents.

Main Results:

• Apathy in FTD correlates with executive dysfunction severity.
• Key brain regions implicated include the prefrontal cortex (dorsolateral, orbitofrontal, medial/ventromedial superior frontal) and cingulate cortex.
• White matter pathways and posterior cortical areas may also contribute to apathy.

Conclusions:

• A revised neurocircuitry model divides apathy into cognitive/planning, initiation, and emotional-affective/motivation subcomponents.
• Recommendations are made to modify bvFTD diagnostic criteria for apathy/inertia.
• bvFTD serves as a valuable model for studying the neurocircuitry of complex behaviors using a lesion-based approach.