The natural history of early-onset Alzheimer's disease (AD) and fronto-temporal dementia (FTD) remains to be described in detail. We seek to describe the natural history of early onset AD and FTD in terms of changes in cognitive assessment and staging, medical history and survival.
Longitudinal prospective cohort analysis.
Neurodegenerative disorders research clinic.
In total, 155 consecutive patients with clinically confirmed sporadic early-onset AD or FTD at a neurodegenerative disorders research clinic in Subiaco, Western Australia (The Artemis Project).
A detailed history was recorded from the patients at baseline, including education, family history and medical history. Mini-mental state exam (MMSE), Global Deterioration Scale (GDS) and total functional capacity (TFC) were determined at each visit from 1994 until 2011. Kaplan-Meier survival analysis was performed.
Patients with FTD were more likely to have a family history of dementia (p=0.026), to develop at least one cerebrovascular risk factor (p=0.003), manifest depression (Fisher's exact p=0.007) and to die during the follow-up period (Pearson χ2 8.97, p=0.003). Kaplan-Meier survival estimates revealed a highly significant difference in the proportion of patients surviving the follow-up period (log rank 7.25, p=0.007) with FTD patients experiencing poorer survival than those with AD. The mean MMSE and TFC were consistently lower in those with FTD compared with those with AD over a decade of follow-up; mean GDS was consistently higher in those with FTD over the follow-up period.
We believe that the difference in survival in patients with AD and FTD in our cohort might relate to the development of one or more cerebrovascular risk factors in FTD patients and the severity of the underlying pathology.