title: Late life bipolar disorder evolving into frontotemporal dementia mimic.
abstract: OBJECTIVE
  Although bipolar disorder has been understood classically as a cyclic disease with full recovery between mood episodes, in the last decade, evidence has accumulated supporting progressive features. The clinical picture of advanced or end-stage bipolar disorder is heterogeneous with possible deficits in cognition and behavior, as illustrated by our case series.
  
  
  METHODS
  From our neuropsychiatric outpatient clinic, we describe four cases with bipolar disorder gradually developing a clinical syndrome, including apathy, disinhibition, loss of empathy, stereotypical behavior, and compulsiveness, fulfilling the criteria for possible behavioral variant frontotemporal dementia. All cases were diagnosed with bipolar 1 disorder at least 10 years before the onset of the current symptoms, which were not due to recent mood episodes or switches of medication. In all cases, 3-7 years of follow-up yielded no progression. Repeated neuroimaging was within normal limits. Cerebrospinal fluid biomarker studies were not supportive of underlying neurodegenerative pathology. C9orf72 mutation status was negative in all cases.
  
  
  CONCLUSIONS
  Symptoms fitting the criteria for possible behavioral variant frontotemporal dementia may be present in end-stage of bipolar disorder. An alternative neurodegenerative nature seems unlikely based on repeated normal neuroimaging and the absence of clinical progression. Functional involvement of the frontal-subcortical networks might play a role.
authors.affiliation: Department of Old Age Psychiatry, GGZInGeest.
authors.forename: Annemiek
authors.initials: A
authors.lastname: Dols
authors.affiliation: Alzheimer Centre and Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Centre, Amsterdam, the Netherlands.
authors.forename: Welmoed
authors.initials: W
authors.lastname: Krudop
authors.affiliation: Alzheimer Centre and Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Centre, Amsterdam, the Netherlands.
authors.forename: Christiane
authors.initials: C
authors.lastname: Möller
authors.affiliation: Department of Geriatric Psychiatry, Sunnybrook Health Science Centre, Faculty of Medicine, University of Toronto, Toronto, Canada.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Shulman
authors.affiliation: Department of Psychiatry and Neurology, Case Western Reserve University School of Medicine, University Hospitals Case Medical Center, Cleveland, OH, USA.
authors.forename: Martha
authors.initials: M
authors.lastname: Sajatovic
authors.affiliation: Alzheimer Centre and Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Centre, Amsterdam, the Netherlands.
authors.forename: Yolande Al
authors.initials: YA
authors.lastname: Pijnenburg
keywords: benign phenocopy syndrome; bipolar disorder; bvFTD; older; staging