The Brain Circuit That Switches Off Chronic Pain

…and other items from this week’s health news:

Pain’s “off switch”

Chronic pain is chronic, that is to say, it is characterized by how it keeps on being there. However, in emergency situations, it’s common for the brain to override pain signals (acute or chronic) in order to function sufficiently to deal with the emergency.

In the case of chronic pain, even outside of emergencies it would be nice for the brain to override those pain signals, in order to function sufficiently to deal with everyday life, not to mention to simply enjoy some respite.

Scientists now understand how: there are special neurons in the brainstem’s lateral parabrachial nucleus that can suppress chronic pain signals when survival instincts—like hunger, thirst, or fear—take priority. These Y1R neurons (as they are called) act as a biological switchboard, helping the brain decide when to prioritize immediate needs over lingering pain. The key? They noticed that hunger seemed to reduce chronic pain more effectively than over-the-counter painkillers.

This means two things, in practical terms:

1. states (like hunger) that the body recognizes as a threat can shut off pain signals—this is obviously not an ideal solution, since it requires creating states the body recognizes as a threat, and those states are usually not good/sustainable ones either
2. new research can now look for ways to flip the switch on these Y1R neurons biochemically, hopefully creating a new class of painkillers that work more effectively and do not have the same drawbacks as, for example, opioids

Read in full: Scientists discover brain circuit that can switch off chronic pain

Related: How Nature Provides Us With A Surprisingly Powerful Painkiller ← this also interrupts the pain signals, albeit in a different way

Cannabis is extra risky for over-65s

Cannabis use is increasing in the US, including among those over 65, though research on long-term effects is still limited because of federal restrictions (the “war on drugs” may have done nothing to reduce drug availability, but has hobbled scientific research for decades).

However, there is still some research, and it’s clear that there are some extra risks for older users, including:

• older adults metabolize cannabis more slowly than younger ones, leading to longer-lasting highs, dizziness, confusion, and higher fall risk
• modern cannabis has far higher THC levels than in past decades (up to 35% in plant form and 90% in concentrates), which means that older adults (accustomed to how things used to be) are more likely to overconsume accidentally, with studies showing tripled emergency visits associated with this
• interactions with medications that are most commonly prescribed to older people—especially blood thinners—can cause further problems too

…in addition to the risks that are closer to the same for everyone, e.g. increased inflammation, cognitive decline, heart disease, heart attacks, and stroke.

Read in full: Regular cannabis use poses risks to those over 65, experts caution

Related: Cannabis Myths vs Reality

HRT: Immune-booster!

Immune function drops sharply after the age of about 60—in men and women, largely due to T-cell production slowing down and eventually all-but-stopping.

For women, there’s usually an additional problem: menopause significantly alters the immune system, leading to more inflammatory white blood cells (monocytes) that are less effective at clearing bacteria and associated with reduced levels of an immune protein essential for fighting infections (it’s called “complement C3”).

However, women have an extra resource at our disposal to give our aging immune systems a boost!

Researchers (Dr. Emma Chambers et al.) found that peri- and post-menopausal women using hormone replacement therapy (HRT) had healthier immune profiles, with fewer inflammatory monocytes, higher complement C3 levels, and infection-fighting capacity closer to that of younger women:

Read in full: Hormone replacement therapy may help restore immunity in menopausal women

Related: Your Brain On (And Off) Estrogen

Take care!