With it, we can communicate our thoughts and feelings

lose ourselves in novels

send text messages

and greet friends

It's hard to imagine being unable to turn thoughts into words

But if the delicate web of language networks in your brain

became disrupted by stroke, illness, or trauma

you could find yourself truly at a loss for words

This disorder, called aphasia, can impair all aspects of communication

People who have aphasia remain as intelligent as ever

They know what they want to say

but can't always get their words to come out correctly

They may unintentionally use substitutions called paraphasias

switching related words, like saying "dog" for "cat",

or words that sound similar, such as "house" for "horse."

Sometimes, their words may even be unrecognizable

There are several types of aphasia grouped into two categories:

fluent, or receptive, aphasia

and non-fluent, or expressive, aphasia

People with fluent aphasia may have normal vocal inflection

but use words that lack meaning

They have difficulty comprehending the speech of others

and are frequently unable to recognize their own speech errors

People with non-fluent aphasia, on the other hand

may have good comprehension

but will experience long hesitations between words and make grammatical errors

We all have that tip-of-the-tongue feeling from time to time

when we can't think of a word

but having aphasia can make it hard to name simple, everyday objects

Even reading and writing can be difficult and frustrating

So how does this language loss happen?

The human brain has two hemispheres

In most people, the left hemisphere governs language

We know this because in 1861

the physician Paul Broca studied a patient

who lost the ability to use all but a single word, "tan."

During a postmortem study of that patient's brain

Broca discovered a large lesion in the left hemisphere

now known as Broca's area

Scientists today believe that Broca's area is responsible in part for naming objects

and coordinating the muscles involved in speech

Behind Broca's area is Wernicke's area near the auditory cortex.

That's where the brain attaches meaning to speech sounds

Damage to Wernicke's area impairs the brain's ability to comprehend language

Aphasia is caused by injury to one or both of these specialized language areas

Fortunately, there are other areas of the brain

which support these language centers

and can assist with communication

Even brain areas that control movement are connected to language

FMRI studies found that when we hear action words, like "run" or "dance"

parts of the brain responsible for movement light up

as if the body was actually running or dancing

Our other hemisphere contributes to language, too

enhancing the rhythm and intonation of our speech

These non-language areas sometimes assist people with aphasia

when communication is difficult.

So how common is aphasia?

Approximately 1 million people in the U.S. alone have it

with an estimated 80,000 new cases per year.

About one-third of stroke survivors suffer from aphasia

making it more prevalent than Parkinson's disease

or multiple sclerosis

yet less widely known

There is one rare form of aphasia called primary progressive aphasia, or PPA,

which is not caused by stroke or brain injury

but is actually a form of dementia

in which language loss is the first symptom

The goal in treating PPA is to maintain language function for as long as possible

before other symptoms of dementia eventually occur

However, when aphasia is acquired from a stroke or brain trauma

language improvement may be achieved through speech therapy

Our brain's ability to repair itself, known as brain plasticity

permits areas surrounding a brain lesion

to take over some functions during the recovery process

Scientists have been conducting experiments using new forms of technology

which they believe may encourage brain plasticity in people with aphasia

Meanwhile, many people with aphasia remain isolated

afraid that others won't understand them or give them extra time to speak

By offering them the time and flexibility to communicate in whatever way they can

you can help open the door to language again,

moving beyond the limitations of aphasia