Late life bipolar disorder evolving into frontotemporal dementia mimic

Area of Science:

• Neuropsychiatry
• Neurodegenerative Diseases
• Bipolar Disorder Research

Background:

• Bipolar disorder is traditionally viewed as a cyclic illness with complete remission between episodes.
• Emerging evidence suggests progressive features in advanced or end-stage bipolar disorder.
• Clinical presentation of advanced bipolar disorder can be heterogeneous, including cognitive and behavioral deficits.

Purpose of the Study:

• To describe a case series of patients with bipolar disorder exhibiting progressive behavioral and cognitive symptoms.
• To investigate the potential overlap between end-stage bipolar disorder and behavioral variant frontotemporal dementia (bvFTD).
• To explore the underlying pathology and neurobiological mechanisms in these cases.

Main Methods:

• Retrospective analysis of four patients diagnosed with bipolar 1 disorder for over 10 years.
• Detailed clinical assessment including behavioral changes (apathy, disinhibition, empathy loss, stereotypy, compulsiveness).
• Longitudinal follow-up (3-7 years), repeated neuroimaging, cerebrospinal fluid biomarker analysis, and genetic testing (C9orf72) were performed.

Main Results:

• All four patients developed a syndrome consistent with possible bvFTD, distinct from acute mood episodes or medication effects.
• No significant progression of symptoms was observed during the follow-up period.
• Neuroimaging and cerebrospinal fluid biomarkers did not indicate underlying neurodegenerative pathology; C9orf72 mutations were negative.

Conclusions:

• Symptoms resembling bvFTD can manifest in the end-stage of bipolar disorder.
• The findings suggest that these presentations are unlikely to be due to a separate neurodegenerative disease.
• Functional alterations within frontal-subcortical brain networks may underlie these observed clinical features in advanced bipolar disorder.