However, abstaining from hallucinogenic drugs, stimulant drugs, managing stress levels, living healthily, and getting plenty of sleep can help reduce the prevalence of hallucinations. In all cases of hallucinations, medical attention should be sought out and informed of ones specific symptoms. Meta-analyses show that cognitive behavioral therapy and metacognitive training can also reduce the severity of hallucinations. Epidemiology
Prevalence of hallucinations varies depending on underlying medical conditions, which sensory modalities are affected, age and culture. As of 2022, auditory hallucinations are the most well studied and most common sensory modality of hallucinations, with an estimated lifetime prevalence of 9.6%. Children and adolescents have been found to experience similar rates (12.7% and 12.4% respectively) which occur mostly during late childhood and adolescence. This is compared with adults and those over 60 (with rates of 5.8% and 4.8% respectively). For those with schizophrenia, the lifetime prevalence of hallucinations is 80% and the estimated prevalence of visual hallucinations is 27%, compared to 79% for auditory hallucinations. A 2019 study suggested 16.2% of adults with hearing impairment experience hallucinations, with prevalence rising to 24% in the most hearing impaired group.A risk factor for multimodal hallucinations is prior experience of unimodal hallucinations. In 90% cases of psychosis, a visual hallucination occurs in combination with another sensory modality, most often being auditory or somatic.
Olfactory
Phantosmia (olfactory hallucinations), smelling an odor that is not actually there, and parosmia (olfactory illusions), inhaling a real odor but perceiving it as different scent than remembered, are distortions to the sense of smell (olfactory system), and in most cases, are not caused by anything serious and will usually go away on their own in time. It can result from a range of conditions such as nasal infections, nasal polyps, dental problems, migraines, head injuries, seizures, strokes, or brain tumors. Environmental exposures can sometimes cause it as well, such as smoking, exposure to certain types of chemicals (e.g., insecticides or solvents), or radiation treatment for head or neck cancer. It can also be a symptom of certain mental disorders such as depression, bipolar disorder, intoxication, substance withdrawal, or psychotic disorders (e.g., schizophrenia). The perceived odors are usually unpleasant and commonly described as smelling burned, foul, spoiled, or rotten. Tactile
Tactile hallucinations are the illusion of tactile sensory input, simulating various types of pressure to the skin or other organs. One subtype of tactile hallucination, formication, is the sensation of insects crawling underneath the skin and is frequently associated with prolonged cocaine use. However, formication may also be the result of normal hormonal changes such as menopause, or disorders such as peripheral neuropathy, high fevers, Lyme disease, skin cancer, and more. Gustatory
This type of hallucination is the perception of taste without a stimulus. These hallucinations, which are typically strange or unpleasant, are relatively common among individuals who have certain types of focal epilepsy, especially temporal lobe epilepsy.