Brain Fog (Mental Haze) Meaning, Symptoms, Causes

We all experience days when we are not able to think very clearly. Our ability to complete mental tasks are impaired, our memory is poor and even our decision-making capacity is not what it usually is. For most of us this is a short term impairment that we commonly refer to as brain fog or mental fog. However, when this impaired mental state is a daily occurrence then it needs to be investigated further as it may be a symptom of some underlying disease.

What is brain fog?

There is no clear clinical definition of the term ‘brain fog’ or ‘mental fog’. It is a common term that people use to describe an impaired mental state and for medical purposes it is often labeled as mental impairment, confusion, poor memory or an inability to concentrate. The activity of the brain is dependent on a host of factors which allows the brain to complete all of its functions.

This activity is largely due to the propagation of electrical impulses in the nerve cells that constitute the brain matter. It is therefore possible that brain fog is due to some impairment in brain activity, coupled with the effect of an imbalance in neurotransmitters (brain hormones), impaired energy production within the brain and/or low oxygen and glucose supply to brain cells.

Meaning and Symptoms

Try to put the meaning of brain fog into words is difficult.  Probably the best way to describe brain fog is like the mental symptoms you experience after missing a night’s sleep or waking up with a hangover. Brain fog is not just fatigue from poor sleep patterns or a hangover as such although it commonly arises in these situations. There is a lack of mental clarity.

Many feel that it is like a haze or fog that has clouded the mental ability. You can still think, concentrate, remember and make decisions but it is not as clear as one is accustomed to. As with most symptoms, brain fog is largely subjective and cannot be clearly measured to isolate a specific abnormality or imbalance. The symptoms of brain fog may include:

  • Forgetfulness (appointments/commitments, names and so on)
  • Poor memory with recalling past events
  • Difficulty concentrating and diminished attention span
  • Slowness with decision-making and learning new things
  • Confusion (sometimes)
  • Mixing up words or forgetting words
  • Easily mentally fatigued with even moderate mental activity

However, these brain fog symptoms are not the same as learning disabilities, mental retardation, or other mental health illnesses.

Brain Fog Causes

It is important to note that the symptoms of brain fog may also be seen in certain neurological and psychiatric conditions. Furthermore, brain fog symptoms are common with using certain drugs and this is known as an iatrogenic cause. However, for most of us brain fog is a transient symptom or collection of symptoms. It comes up occasionally, lasts for a short period of time and usually we can clearly identify the cause. Here are some of the common causes.

Insufficient Sleep

Sleep is important for physical, mental and emotional well being. The exact way in which sleep benefits the body is unclear but it is known that there are a host of imbalances that arise with inadequate sleep or poor quality sleep. The period of time during which we sleep is essentially a recharging session. Therefore inadequate sleep will understandably have an effect on mental functioning which may be described as brain fog. It may also be described as a morning muzzy feeling.

Alcohol Overindulgence

Excessive alcohol consumption can impair brain functioning for hours or days afterwards. In chronic alcoholism, it can cause permanent changes and damage to the brain structure and its activity. Initially brain fog is part of intoxication. The lack of mental clarity when drunk is well understood. Most of us look at brain fog following an overindulgence in alcohol as part of a hangover. However, it usually subsides with time and rest and mental clarity restores provided that there is no further alcohol intake.

Illicit Drug Use

Illicit substances act on the brain in different ways. Some of these suppress nervous system activity while others stimulate it excessively for short periods of time. The nervous system disruptions vary but drugs like cocaine, MDMA and heroin causes bursts of neurotransmitter secretions temporarily. This impairs normal brain functioning despite the euphoria making a person think that their brain function has improved. The after effects are just as debilitating and brain fog is one of the many symptoms that can persist for day, weeks or even months thereafter.

Prescription Drug Use

A number of prescription drugs can affect brain activity as well. Often these effects are not as severe and uncontrollable as with illicit drugs. Sedatives, tranquilizers or anti-anxiety medication, antidepressants, anti-psychotics and narcotic painkillers are probably best known for its effect on brain activity. However, similar side effects may arise with other drugs some of which are not even intended to treated nervous system conditions.

Mental Exertion

Any strenuous or prolonged mental activity that is well above the norm coupled with physical fatigue may lead to the symptoms described as brain fog. It is often easily remedies with a good night’s sleep and some relaxation techniques that does not involve extensive mental activity. This effect from mental exertion is not uncommon but it is usually temporary. Even repeated episodes of such mental exertion usually does not lead to permanent brain fog.

Emotional Stress

Emotional stress can have a range of effects on mental activity. It can be prolonged stress like continuing marital problems or a sudden emotional shock like the death of a loved one and the accompanying grief. The resulting brain fog in these cases is directly related to the events or situation. However, sometimes past events that were emotionally taxing may have an impact many years or even decades later. Brain fog may therefore be linked to this past trauma, as is seen with childhood abuse.

Low Blood Glucose or Oxygen

An adequate supply of glucose and oxygen is necessary for the brain to function optimally. Even a momentary dip in blood oxygen and glucose can affect the brain. Therefore any condition that lowers brain glucose or oxygen levels will impact normal brain activity and give rise to brain fog. It may be seen in endocrine, cardiovascular and respiratory diseases. Poor air quality, extreme dieting, prolonged fasting and so on may all contribute to this mental impairment. It may also occur with nutritional deficiencies.

Diseases and Other Causes

Brain fog symptoms may be also be seen in these conditions but it depends on the stage and severity of the disease.

  • Anemia (severe)
  • Brain diseases like Alzheimer’s disease, Creutzfeldt-Jakob disease (CJD), Parkinson’s disease
  • Brain atrophy (any cause)
  • Chronic alcoholism (Korsakoff syndrome or Wernicke’s encephalopathy)
  • Concussion and post-concussion syndrome
  • Depression
  • Diabetes mellitus (usually uncontrolled)
  • Encephalitis
  • Heavy metal toxicity
  • Heart failure
  • Hypothyroidism
  • Liver disease
  • Meningitis
  • Post traumatic stress disorder (PTSD)
  • Sleep apnea
  • Stroke and transient ischemic attacks (TIA)
