Frontotemporale Demenz: Neurotransmitter und klinische Symptomatik im Fokus therapeutischer Überlegungen

Cholinergic Neurons in Nucleus Subputaminalis in Primary Progressive Aphasia

BACKGROUND

Primary Progressive Aphasia (PPA) is a syndrome characterized by an isolated impairment of language function at disease onset. The cholinergic system is implicated in language function and cholinergic deficits are seen in the brains of individuals with PPA. One major source of cholinergic innervation of the cerebral cortex is the nucleus basalis of Meynert (NBM) within which lies the nucleus subputaminalis (NSP). This nucleus is postulated to be involved in language function. We compared the abundance of cholinergic neurons in the NBM and NSP of controls and individuals with PPA. Also explored was whether the individuals presenting with PPA, who subsequently developed different clinical and neuropathological profiles, showed similar cholinergic deficits in the NSP.

METHODS

Cytoarchitecture of the basal forebrain was studied using Nissl staining in control (n = 5) and PPA (n = 5) brains. Choline acetyltransferase (ChAT) immunohistochemical staining labeled cholinergic neurons were quantified using Neurolucida software.

RESULTS

In comparison to matched controls, PPA showed reduction of cholinergic neurons in the NBM (t(8) = 4.04, p = 0.0037; Cohen's effect size value d = 2.62) and the NSP (t(6) = 4.62, p = 0.0042; Cohen's d effect size d = 2.92). The average percent of cholinergic neuronal loss was relatively higher in the NSP (64.7%) compared to the NBM (47.7%).

CONCLUSION

Regardless of underlying pathology, all cases presenting with PPA showed a marked loss of cholinergic neurons in the NSP, providing further evidence for the importance of this nucleus in language function.

Repetitive transcranial magnetic stimulation influences mood in healthy male volunteers

The influence of repetitive transcranial magnetic stimulation (rTMS) on mood in healthy people is uncertain, as former studies show divergent results. Previous studies in healthy volunteers focused exclusively on the immediate effect of a single session of rTMS. In contrast the aim of this randomised sham-controlled study was to analyse the influence on mood of a series of 9 High Frequency (HF) rTMS stimulations of the left dorsolateral prefrontal cortex (DLPFC). 44 young healthy male volunteers were randomly assigned to receive 9 sessions of active HF-rTMS (n = 22) or sham rTMS (n = 22) over the left DLPFC. Each session in the active group consisted of 15 trains of 25 Hz starting with 100% of motor threshold. Sham stimulation was performed following the same protocol, but using a sham coil. The variables of interest were the Beck Depression Inventory (BDI) and six Visual Analogue Scales (VAS) which quantified "mood", "enjoyment" and "energy". We found a significant reduction of the BDI sum score in the active group (GLM, p < 0.001) whereas no significant changes of the BDI sum score were caused by sham stimulation (GLM, p = 0.109). The BDI single item analyses revealed within and between group differences supporting the modifying effect of rTMS on BDI. According to the employed VAS we did not find significant differences caused by active or sham stimulation in five of six VAS. In the VAS labelled lively/gloomy the active group was found to be more "gloomy" (p = 0.0111) immediately after stimulation. Our data show that a 9-day long series of HF-rTMS of the left DLPFC improves mood, analysed by BDI in healthy young men, whereas no significant long-term changes were found in VAS.