New York, May 2 : Doing simple breathing exercises may help reduce risk of developing Alzheimer's disease, claimed a study. Researchers from the University of Southern California showed that a brief breathing session -- inhaling for a count of five, then exhaling for a count of five for 20 minutes twice a day for four weeks can have significant impacts. Volunteers' heart rate variability increased during each exercise period and the levels of amyloid-beta peptides circulating in their blood decreased over the four weeks of the experiment. Accumulation of amyloid beta in the brain due to increased production and/or decreased clearance is believed to trigger the Alzheimer's disease process. The study, published in the journal Scientific Reports, may be the first to discover a way that adults, both young and old, can reduce their amyloid beta levels: via breathing exercises that lower the levels in our blood of these peptides associated with Alzheimer's disease, the team said. It is because the way we breathe affects our heart rate, which in turn affects our nervous system and the way our brain produces proteins and clears them away, they explained. In the study, the team asked 108 participants, (half were young -- aged 18 to 30 and half were old -- aged 55 to 80), to do the exercises twice a day, for 20 minutes at a time. The team also monitored their heart rates, which tended to rise in peaks as they inhaled and dip down to baseline as they exhaled. Their goal was to increase the breathing-induced oscillations in their heart rate. The researchers took blood samples before the participants began the experiment and again, after four weeks. They examined the plasma of participants from both groups, looking for amyloid beta peptides 40 and 42. They found that plasma levels of both peptides decreased in the group who breathed slowly and tried to increase their heart rate variability (HRV) by increasing oscillations. The younger and the older adults also showed similar effects of the interventions on plasma amyloid beta levels. "At least to date, exercise interventions have not decreased amyloid beta levels," said Professor Mara Mather, who directs the Emotion and Cognition Lab at USC's Leonard Davis School of Gerontology. "Regularly practising slow-paced breathing via HRV exercise may be a low-cost and low-risk way to reduce plasma amyloid beta levels and to keep them low throughout adulthood," Mather added. /IANS