Heat Intolerance and Cognitive Symptoms
Many people with certain health conditions struggle when temperatures rise. Heat intolerance means the body has trouble handling warmth, leading to a range of problems. This often ties into issues with the autonomic nervous system, which controls things like body temperature, blood pressure, and heart rate. When it does not work right, called dysautonomia, heat can make everyday tasks harder.
One common sign is orthostatic hypotension. This happens when standing up causes blood pressure to drop too low. People feel dizzy, lightheaded, or tired. They might also get blurry vision, nausea, headaches, weakness, heart palpitations, or shortness of breath. Brain fog sets in, making it hard to think clearly or focus. These cognitive symptoms, like fuzzy thinking, come from poor blood flow to the brain during heat exposure.
In multiple sclerosis, heat sensitivity is a key issue. Warm showers, hot weather, or exercise can worsen symptoms. Nerves that are already damaged react badly to heat, slowing signals in the body. This leads to more fatigue and mental cloudiness, where concentration slips and memory feels off.
Other dysautonomia types bring similar heat troubles. For example, noncardiogenic vasovagal syncope causes fainting from low blood pressure and heart rate in the heat. Before passing out, people feel clammy, sweaty, nauseated, warm, or flushed. Vision grays out, and hearing changes, adding to confusion. Autoimmune autonomic ganglionopathy brings dry mouth, burning in limbs, and stomach slowdowns, all amplified by heat and linked to thinking issues.
Pure autonomic failure, more common in middle-aged men, causes severe dizziness and fainting. It connects to Parkinson’s and dementia, where heat intolerance speeds up cognitive decline like memory loss or slowed processing.
These problems stem from unstable body temperature regulation. The body cannot cool itself well, so blood vessels and nerves falter. Cognitive symptoms show up as brain fog, poor focus, or slowed reactions because the brain lacks steady oxygen and nutrients in the heat.
Managing this starts with avoiding triggers. Stay cool with fans, cold drinks, and light clothes. Rise slowly from sitting to prevent blood pressure drops. For those with MS or dysautonomia, doctors might suggest cooling vests or medications to steady blood pressure.
Sources
https://www.webmd.com/brain/dysautonomia-overview
https://themighty.com/topic/multiple-sclerosis/weird-early-ms-signs/
