Once the cases were identified through searching the existing database, patients with clinical presentation of language-variant FTD were excluded.13 K.A.J. previously reviewed all records throughout the disease course to ensure that the patient met or eventually met consensus criteria for bvFTD,1 even though at the time of initial clinical evaluation (1970-2006), the diagnosis recorded may not have been FTD.7 K.A.J. then removed the final pathologic diagnosis from patient records. Cases were included in this study if a behavioral neurologist evaluated patients who had sufficiently detailed history and there was no coexisting pathology that could account for some of the clinical symptoms. W.T.H. then retrospectively reviewed historical records from the initial clinical visits of all cases in a blinded fashion. Clinical information on initial neurological evaluation was then abstracted. Symptoms were considered present if they constituted significant complaints by patients and family members. Clinical signs were considered present only if a behavioral neurologist definitively recognized them and they could not be explained by another etiology. Behavioral features were considered absent if they were explicitly stated as such or their presence was not mentioned. Because a behavioral neurologist with expertise in FTD examined all patients, the inclusion of symptoms in this study required the symptom to be of at least a mild to moderate severity. We paid special attention to clinical characteristics outlined in the consensus diagnostic criteria of bvFTD, including core features, supportive features, and exclusion criteria. These include personality and behavior change, decline in social interpersonal conduct, impaired regulation of personal conduct, emotional blunting, and poor planning and/or judgment (including poor organization and poor problem solving in daily activities or at work); loss of insight, decline in personal hygiene and grooming, hyperorality, dietary change, perseverative and/or repetitive behavior, loss of empathy, speech and language dysfunction, and incontinence; motor symptoms including parkinsonism, spasticity, or myoclonus; and delusions and/or paranoia, forgetfulness and/or amnesia, topographical disorientation, and deficits in facial recognition. Some of these patients may have had minor symptoms related to previous psychiatric or other comorbid illnesses; thus, consideration was given to dominant symptoms.6 An additional feature of hypersomnolence was included, as a number of patients' family members shared a complaint that the patients slept all day. Features of mental rigidity and inflexibility, distractibility and impersistence, utilization behavior, and logoclonic speech were not found in the patients' records and were therefore not included in the statistical analysis. Primitive reflexes were also excluded as they were inconsistently documented. Additional information that was abstracted included patients' age at onset, age at initial evaluation, duration of disease (time from symptomatic onset to death), sex, family history of dementia (including FTD and other nonstroke-related cognitive impairment) and/or MND, and any abnormality on cerebral spinal fluid examination.