Increased CSF APPs-α levels in patients with Alzheimer disease treated with acitretin

Objective: Authors investigated induction of α-secretase A disintegrin and metalloprotease 10 (ADAM10) by the synthetic retinoid acitretin (Neotigason; Actavis, München-Riem, Germany) in patients with mild to moderate Alzheimer disease (AD) via measurement of CSF content of α-secretase–derived amyloid precursor protein (APPs-α).

Methods: Twenty-one patients clinically diagnosed with mild to moderate AD received acitretin (30 mg per day) or placebo in a 4-week double-blind study. Primary endpoint was the difference of CSF APPs-α ratios calculated from the APPs-α levels after treatment and at baseline. We monitored safety and tolerability of the treatment. In addition, we assessed biomarkers such as β-amyloid 42 (Aβ₄₂) under treatment conditions.

Results: The acitretin group showed a significant increase in CSF APPs-α levels compared with the placebo group (difference 0.38, 95% confidence interval 0.03–0.72, p = 0.035) within this rather short treatment period. The synthetic retinoid acitretin was overall safe and well tolerated.

Conclusions: Our pilot study highlights that acitretin is able to enhance the nonamyloidogenic APP processing in human patients. Clinical consequences of this regulation should be investigated in larger and longer trials in patients with AD to evaluate acitretin's potential to serve as a novel therapeutic drug.

Classification of evidence: This study provides Class III evidence that in patients with AD, oral acitretin increases CSF APPs-α levels.

Reference: Neurology 10.1212/WNL.0000000000001017

Anatomical heterogeneity of Alzheimer disease

Objective: Because the signs associated with dementia due to Alzheimer disease (AD) can be heterogeneous, the goal of this study was to use 3-dimensional MRI to examine the various patterns of cortical atrophy that can be associated with dementia of AD type, and to investigate whether AD dementia can be categorized into anatomical subtypes.

Methods: High-resolution T1-weighted volumetric MRIs were taken of 152 patients in their earlier stages of AD dementia. The images were processed to measure cortical thickness, and hierarchical agglomerative cluster analysis was performed using Ward's clustering linkage. The identified clusters of patients were compared with an age- and sex-matched control group using a general linear model.

Results: There were several distinct patterns of cortical atrophy and the number of patterns varied according to the level of cluster analyses. At the 3-cluster level, patients were divided into (1) bilateral medial temporal–dominant atrophy subtype (n = 52, ∼34.2%), (2) parietal-dominant subtype (n = 28, ∼18.4%) in which the bilateral parietal lobes, the precuneus, along with bilateral dorsolateral frontal lobes, were atrophic, and (3) diffuse atrophy subtype (n = 72, ∼47.4%) in which nearly all association cortices revealed atrophy. These 3 subtypes also differed in their demographic and clinical features.

Conclusions: This cluster analysis of cortical thickness of the entire brain showed that AD dementia in the earlier stages can be categorized into various anatomical subtypes, with distinct clinical features.

Reference: Neurology 10.1212/WNL.0000000000001003