To investigate trajectories of cognitive decline in patients with different types of dementia compared to controls in a longitudinal study.

In 199 patients with Alzheimer's disease (AD), 10 with vascular dementia (VaD), 26 with dementia with Lewy bodies (DLB), 20 with behavioural variant frontotemporal dementia (bvFTD), 15 with language variant frontotemporal dementia (lvFTD) and 112 controls we assessed five cognitive domains: memory, language, attention, executive and visuospatial functioning, and global cognition (Mini-Mental State Examination, MMSE). All subjects had at least two neuropsychological assessments (median 2, range 2–7). Neuropsychological data were standardized into z scores using baseline performance of controls as reference. Linear mixed models (LMMs) were used to estimate baseline cognitive functioning and cognitive decline over time for each group, adjusted for age, gender and education.

At baseline, patients with dementia performed worse than controls in all cognitive domains (p < 0.05) except visuospatial functioning, which was only impaired in patients with AD and DLB (p < 0.001). During follow-up, patients with AD declined in all cognitive domains (p < 0.001). DLB showed decline in every cognitive domain except language and global cognition. bvFTD showed rapid decline in memory, language, attention and executive functioning (all p < 0.01) whereas visuospatial functioning remained fairly stable. lvFTD declined mostly in attention and executive functioning (p < 0.01). VaD showed decline in attention and executive functioning.

We show cognitive trajectories of different types of dementia. These estimations of natural disease course have important value for the design of clinical trials as neuropsychological measures are increasingly being used as outcome measures.

The extent to which specific factors influence diagnostic delays in dementia is unclear. Therefore, the aim of the present study was to compare duration from symptom onset to diagnosis for young-onset dementia (YOD) and late-onset dementia (LOD) and to assess the effect of age at onset, type of dementia, gender, living situation, education and family history of dementia on this duration.

Data on 235 YOD and 167 LOD patients collected from caregivers from two prospective cohort studies were used. Multiple linear regression analysis was performed.

The duration between symptom onset and the diagnosis of YOD exceeded that of LOD by an average of 1.6 years (2.8 v. 4.4 years). Young age and being diagnosed with frontotemporal dementia were related to increases in the time to diagnosis. Subjects with vascular dementia experienced shorter time to diagnosis.

There is a need to raise special awareness of YOD to facilitate a timely diagnosis.

We aimed to compare the rate of cognitive decline in patients with early and late onset Alzheimer's disease (AD) and to investigate the potentially modifying influence of the apolipoprotein E (APOE) genotype.

We included 99 patients with early onset AD (age ⩽65 years) and 192 patients with late onset AD (age >65 years) who had at least two scores on the Mini-Mental State Examination (MMSE) (range 2–14) obtained at least 1 year apart. Linear mixed models were performed to investigate the rate of cognitive decline dependent on age at onset (AAO) and APOE genotype.

The mean (s.d.) age for patients with early onset AD was 57.7 (4.5) years, and 74.5 (5.1) years for patients with late onset AD. AAO was not associated with baseline MMSE [β (s.e.)=0.8 (0.5), p=0.14]. However, patients with early onset showed a faster decline on the MMSE [β (s.e.)=2.4 (0.1) points/year] than those with late onset [β (s.e.)=1.7 (0.1) points/year, p=0.00]. After stratification according to APOE genotype, APOE ε4 non-carriers with early onset showed faster cognitive decline than non-carriers with late onset [2.4 (0.3) v. 1.3 (0.3) points/year, p=0.01]. In APOE ε4 carriers, no difference in rate of cognitive decline was found between patients with early and late onset [β (s.e.)=0.2 (0.2), p=0.47].

Patients with early onset AD show more rapid cognitive decline than patients with late onset, suggesting that early onset AD follows a more aggressive course. Furthermore, this effect seems to be most prominent in patients with early onset who do not carry the genetic APOE ε4 risk factor for AD.