According to the Daily Mirror reports “An ‘exercise pill’ mimicking the effects of a gym workout could prevent Alzheimer’s disease”. Actually pill is a reference to a protein called irisin. Irisin has been dubbed the “exercise hormone” because previous research found it’s released from muscles in response to physical activity.
Researchers wanted to find that if irisin, or the lack of it, had any role or impact in Alzheimer’s disease. This is because irisin has previously been found in the area of the brain called the hippocampus, which is involved with learning and memory. Both these cognitive functions are adversely affected by Alzheimer’s.
Researcher Approaches & Findings
- The researchers looked at post-mortem brain specimens from elderly adults.
- They found people who’d had advanced Alzheimer’s had lower levels of irisin in the hippocampus than people who’d had earlier stage disease or normal brain function.
- They then carried out experiments in mice bred to have an Alzheimer’s-like condition.
- They found blocking irisin production worsened the mice’s memory and learning.
- Boosting irisin levels through a daily swimming programme helped to improve memory and learning.
- These are interesting findings that may help improve our understanding of Alzheimer’s.
- But at this stage there’s no evidence that exercise will directly prevent Alzheimer’s, or restore brain function in those with the disease. Further studies in people with Alzheimer’s are needed.
The most point in this study is that it supports the idea that physical activity may reduce the risk of many long-term diseases and may preserve brain health as we age.
Basic Finding & Results
This study confirmed that irisin was present in the hippocampus of the mouse and human brains.
- They found levels were lower in mice with Alzheimer’s-type disease.
- They were also lower in humans with late-stage Alzheimer’s compared with controls or those with earlier stage disease.
- They found higher levels of amyloid in humans and rodent brains were associated with reduced irisin levels.
- Knocking out irisin did not affect memory or behaviour in normal mice. But it did affect test performance in the Alzheimer’s mice.
- They found the absence of irisin affected the ability of the mouse brains to form new nerve connections.
- The researchers confirmed that boosting irisin levels in the Alzheimer’s mice restored their memory defects and the ability to form new nerve connections.
- They also showed that giving Alzheimer’s mice an “exercise regime” of daily swimming boosted their hippocampal irisin levels.
Researchers Interpretation of Outcome
The researchers said their findings “place FNDC5/irisin as a novel agent capable of opposing [nerve connection] failure and memory impairment in Alzheimer’s disease”. They suggested that exercise could be a way to increase hippocampal irisin levels in people at risk of Alzheimer’s or in those who already have cognitive impairment.
This is an interesting study that seems to show that the memory and learning region of the brain in those with Alzheimer’s has lower levels of the protein irisin. But what this actually means is an entirely different question. It could be that low physical activity levels during the person’s lifetime has led to lower levels of irisin in the brain, and that this has led to the development of Alzheimer’s. An alternative explanation could be that brain changes that occur during Alzheimer’s prevent irisin accumulating to the same extent. There’s also the possibility that people with advanced Alzheimer’s do less activity because of their illness and this is why they have low levels of irisin. The good point about this study is that the study doesn’t alone explain the potential role of irisin. The found that restoring irisin in Alzheimer’s mice, including by daily swimming, can boost memory and nerve connections. The causes of Alzheimer’s remain poorly understood, but a healthy lifestyle that includes a balanced diet, regular exercise, not smoking and only drinking alcohol in moderation may all help preserve brain health as we age.