Behavioral variant frontotemporal dementia and late onset schizophrenia
Presentation
55 year old female with late onset Schizophrenia presents with one year history of social withdrawal, self-neglect, global cognitive decline and irritability. Her CSF study revealed ABeta1-42 (360) and phosphorylated- (55) and total-Tau (340). ASL and SPECT are demonstrated.
Patient Data
MRI brain + ASL
Moderate frontal and moderate-severe parietal lobe atrophy with more atrophy on right side. Hippocampi are relatively preserved. Mild white matter small vessel disease on frontal horns.
This arterial spin labeling (ASL) fMRI scan shows reduced perfusion anteriorly with hyperperfusion in the posterior cingulate and medial parietal area, which is in keeping with FTD.
SPECT (see below) showed hypometabolic changes similar to MRI and ASL, with additional mild hypometabolism in medial parietal lobes.
There is diffuse cerebral hypoperfusion involving all lobes bilaterally,
with relative sparing of the occipital lobe, basal ganglia and the cerebellum.
Case Discussion
Late-onset schizophrenia (LOS) occurs after the age of 40, and most researchers classify onset after 60 as a very late onset schizophrenia. LOS has different demographic, clinical and neuropsychological characteristics than regular schizophrenia1. A subset of LOS may present with cognitive and behavioral impairment consistent with young-onset Frontotemporal Dementia (FTD)2. However, differentiating FTD from LOS can be difficult at the initial phase, which may delay the diagnosis (mean time 4-5 years from the first onset of psychosis).
Arterial spin labeling (ASL) is a type of fMRI which measures tissue perfusion with an intrinsic tracer3,4. The relatively simple and cost-effective option than FDG-PET scans makes ASL a potential imaging modality for making a clinical diagnosis of dementia. In this study, a correlation between ASL and SPECT is demonstrated. ASL finding in the study is consistent with FTD5.
A genetic study is pending and the current working diagnosis is behavioral variant FTD.