[Frontotemporal dementia and schizophrenia in later life: a comparison of executive and general cognitive functioning]

BACKGROUND

Frontotemporal dementia (FTD) is characterised clinically by progressive changes in behaviour and personality; these changes are followed by cognitive disorder. FTD needs to be differentiated from other forms of dementia and from psychiatric conditions such as schizophrenia. Both FTD and schizophrenia lead to cognitive disorders and particularly to executive impairments.

AIM

To compare executive and general cognitive functioning in patients with FTD and in patients with schizophrenia in later life.

METHOD

As cognitive screening instruments we used the 'Frontal Assessment Battery' (FAB) and the 'Mini-Mental State Examination' (MMSE). The FAB en MMSE test results (retrieved from the database of the Alzheimer centre of the VU medical centre) for 25 outpatients diagnosed as having FTD were compared with the test results (retrieved from the 'SOUL' study database) for 31 elderly schizophrenia patients.

RESULTS

In both the fab and the MMSE tests the scores for the patients with FTD were significantly lower than the scores for the patients with schizophrenia.

CONCLUSION

Our study suggests that, despite the clinical similarities, there are differences between patients with FTD and elderly patients with schizophrenia with regard to executive and general cognitive functioning. Further studies are needed in order to differentiate between the two illnesses.

CSF biomarkers predict rate of cognitive decline in Alzheimer disease

OBJECTIVE

CSF biomarkers amyloid beta 1-42 (Abeta(42)), total tau (tau), and tau phosphorylated at threonine 181 (p-tau-181) are useful diagnostic markers for Alzheimer disease (AD). Less is known about these biomarkers as predictors for further cognitive decline in patients with AD. We hypothesized that high tau, especially in combination with relatively low p-tau-181, is a marker of rapid decline, since it has been associated with fast neuronal degeneration.

METHODS

A total of 151 patients with AD of whom we had baseline CSF were included from our memory clinic. All patients had at least 2 Mini-Mental State Examination (MMSE) scores, obtained no less than 1 year apart. Linear mixed models were used to assess associations between CSF biomarkers and the rate of cognitive decline as measured with the MMSE. CSF biomarkers were used in quintiles, random intercept and random slope with time were assumed, and the analyses were corrected for sex and age.

RESULTS

The patients with AD (45% women, age 66 +/- 9 years, baseline MMSE 22 +/- 4) had a follow-up period of 2.0 (1.0-5.0) years. Linear mixed models revealed no relations between any CSF biomarker and baseline MMSE. However, CSF biomarkers did predict cognitive decline over time. A low p-tau-181/tau ratio was the strongest predictor with a dose-dependent effect (lowest vs highest quintile: 2.9 vs 1.3 MMSE points annual decline, p for trend <0.001). In addition, low Abeta(42), high tau, and high tau/Abeta(42)-ratio were associated with rapid cognitive decline (p < 0.05).

CONCLUSION

At the time of diagnosis, a combination of high CSF tau without proportionally elevated p-tau-181 is associated with a faster rate of cognitive decline.

Most rapid cognitive decline in APOE epsilon4 negative Alzheimer's disease with early onset

BACKGROUND

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.

METHOD

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.

RESULTS

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 [beta (S.E.)=0.8 (0.5), p=0.14]. However, patients with early onset showed a faster decline on the MMSE [beta (S.E.)=2.4 (0.1) points/year] than those with late onset [beta (S.E.)=1.7 (0.1) points/year, p=0.00]. After stratification according to APOE genotype, APOE epsilon4 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 epsilon4 carriers, no difference in rate of cognitive decline was found between patients with early and late onset [beta (S.E.)=0.2 (0.2), p=0.47].

CONCLUSION

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 epsilon4 risk factor for AD.

CSF biomarkers in relationship to cognitive profiles in Alzheimer disease

OBJECTIVE

To investigate the relationship between CSF biomarkers and cognitive profiles in Alzheimer disease (AD).

METHODS

We included 177 patients with AD. Digit Span, Visual Association Test (VAT), VAT object naming, Trail Making Test (TMT), and category fluency were used to assess cognitive functions. Disease severity was assessed using Mini-Mental State Examination; functional impairment was rated by Clinical Dementia Rating. In CSF, levels of amyloid-beta 1-42 (Abeta(1-42)), tau, and tau phosphorylated at threonine 181 (p-tau) were measured. K-means cluster analysis was performed with the three biomarkers to obtain three clusters. Multivariate analysis of variance for repeated measures was performed with CSF cluster as between-subjects factor, neuropsychological z scores as within-subjects variable, and age, sex, and education as covariates.

RESULTS

Cluster 1 consisted of 88 patients (49%) with relatively high levels of Abeta(1-42) and low levels of tau and p-tau. Cluster 2 contained 72 patients (41%) with relatively low levels of Abeta(1-42) and high levels of tau and p-tau. Cluster 3 was made up of 17 patients (10%) with low levels of Abeta(1-42) and very high levels of tau and p-tau. No differences between clusters on age, sex, education, APOE genotype, disease duration, functional impairment, or disease severity were found. Patients in cluster 3 performed worse on VAT, TMT-A and -B, and fluency.

CONCLUSIONS

Clusters of CSF biomarker levels are related to cognitive profiles in Alzheimer disease. A subgroup of patients with extremely high CSF levels of tau and tau phosphorylated at threonine 181 shows a distinct cognitive profile with more severe impairment of memory, mental speed, and executive functions, which cannot be explained by disease severity.