The effects of divided attention on speech in Parkinson's disease (PD) have been studied for a variety of tasks in recent years. Much of the previous research studied gait patterns while participants concurrently performed another task. There have been few studies regarding the effects of divided attention on speech in individuals with PD. The ability to communicate effectively relies in part on an appropriate rate of speech, vocal intensity, and fundamental frequency control. This study included 27 participants: 8 with PD, 12 neurologically healthy older (HO) adults, and 7 healthy younger (HY) adults. Each participant was given a list of topics to speak about during the experiment. They produced monologues under three conditions: standing, walking on a treadmill, and walking over obstacles on a treadmill. Each monologue was recorded and trimmed of pauses between topics, experimenter speech, and nonspeech behaviors before analysis. Speech rate, speaking versus pausing time, overall intensity, and intensity and fundamental frequency (F0) variability were analyzed. Median, mean, maximum, and minimum F0 increased as the gait task increased in difficulty. Mean and standard deviation of intensity also increased with gait demands. All groups had increased intensity variability when walking compared to standing. Speaking versus pausing time did not differ significantly as a function of the walking task and the results varied across the groups; the same was true for speech rate. These findings reflect changes in performance during divided attention tasks, with a greater effect on HO adults and individuals with PD than their younger counterparts.

In dieser Arbeit wird in mehreren Experimenten untersucht, wie gut junge und alte Erwachsene Sätze mit unterschiedlich komplexer syntaktischer Struktur verstehen können. Zentrales Thema dabei sind die Schwierigkeiten, die ältere Erwachsene mit der Objekt-vor-Subjekt-Wortstellung haben. Untersucht wird, inwiefern diese beobachteten Altersunterschiede durch eine reduzierte verbale Arbeitsgedächtniskapazität der älteren Erwachsenen erklärt werden können. Dabei stellt sich die Frage, ob die Defizite ein generelles verbales Arbeitsgedächtnis betreffen oder ob es ein eigenes Verarbeitungs-system für syntaktische Informationen gibt, dessen Kapazität mit dem Alter abnimmt. Es wurde versucht, die postulierte reduzierte Arbeitsgedächtniskapazität der älteren Erwachsenen an jungen Erwachsenen zu simulieren, indem deren Arbeitsgedächtniska-pazität durch eine Zusatzaufgabe künstlich eingeschränkt wurde. Weiterhin wurden die Altersunterschiede bei syntaktisch komplexen zentraleingebetteten Relativsätzen mit denen bei syntaktisch einfacheren koordinierten Hauptsätzen verglichen. Um die Studienteilnehmer mit den seltenen objektinitialen Strukturen zu konfrontieren und ihre Erfahrung mit solchen Sätzen zu verändern, wurden schließlich sowohl junge als auch alte Erwachsene mit Sätzen mit Objekt-vor-Subjekt-Wortstellung trainiert. / In this paper several experiments about age differences in comprehension of sentences with different syntactical structure are reported. The main focus is on the difficulties old adults experience when a sentence starts with an object. Can the age differences be explained by differences in working memory capacity? Have old adults less working memory capacity, or does there exist a separate working memory for syntactic information which declines with age? In an age simulation, young adults working memory capacity was reduced by an additional digit load. Age differences in comprehension of syntactical complex sentences were compared with age differences in sentences with less complex syntactical structure. To change their experience with the rare object initial word order participants were trained with object initial sentences.