When a family member has just had a stroke, families most often ask: "They cannot speak or understand after the stroke. Will they get better?" The answer is: most patients recover to some degree, but how far they recover differs from person to person. This article therefore gives a range and not a single number. One more point needs to be made first: aphasia is damage to the pathway for language and is not a decline in intelligence. When a patient cannot speak or cannot understand, it does not mean that the patient no longer understands what goes on around them.
Aphasia is quite common after stroke. A systematic review and meta-analysis found that the median prevalence of aphasia in mixed stroke populations was about 30% in the acute phase and about 34% in the rehabilitation phase (Flowers et al., 2016). Speech therapy works: a Cochrane systematic review (57 RCTs, 3002 patients) found that speech therapy clearly improved functional communication compared with no therapy (SMD 0.28; Brady et al., 2016). The sections below cover the recovery process and outlook: whether recovery happens, how long it takes, how far it goes and what decides the outlook.
The recovery process of aphasia and how it changes over time
Recovery from aphasia is not a straight line. It is fast at first and then slows, levelling off at about six months. The largest gains come in the first few weeks to three months after the stroke, and after that natural recovery slows clearly. A very early study followed 21 patients with aphasia, of whom 19 had improved within the first 15 days after the stroke, and overall language improved almost in a straight line at about 1.07 points per week (on a 10-point scale), mainly in expressive language (Wilson et al., 2019). At a larger population level, Pedersen and colleagues (1995) followed 881 patients with acute stroke and found that about 38% had aphasia on admission, falling to 18% at discharge. The time for language function to level off was about 2 weeks for mild, about 6 weeks for moderate and about 10 weeks for severe.
A slowing of recovery does not mean the end point has been reached. At about six months after the stroke, the natural recovery of language function slows down, which is usually called a plateau. This refers only to the natural recovery of the body slowing. It does not mean that therapy is of no use. As described below, even in the chronic phase patients can still make real progress when they have enough hours of targeted speech therapy. The stages of rehabilitation from aphasia follow those of stroke rehabilitation as a whole. For the general stages and timing of stroke recovery, see the article on the stroke recovery timeline, and for the overall service see home stroke rehabilitation.
Key factors that decide the extent of recovery from aphasia
The initial severity of the aphasia is the strongest predictor of long-term recovery. One review concluded that the next factors are the site and size of the damage, and that patient factors such as sex, handedness, age and education have weaker predictive power (Plowman et al., 2012). The results of Pedersen and colleagues agree: the language outcome after one year was predicted by the initial severity of the aphasia and the initial severity of the stroke, and not by age, sex or type of aphasia (Pedersen et al., 1995; 2004).
Age and timing of therapy: linked, but not a cause. The RELEASE individual participant data meta-analysis (5928 IPD, 174 studies) found that patients who were younger (<55 years) and who started intervention earlier (enrolled <1 month after onset) had the largest language recovery. For example, those enrolled <1 month after onset improved overall language by about +19.1 WAB-AQ points (CI 13.9–24.4) (RELEASE Collaborators, 2021). However, this is a correlation analysis of large data (which kinds of people improved more) and cannot prove cause, and the benefit of early intervention may also be affected by other confounding factors.
Common types of aphasia and their recovery
Aphasia can be divided broadly into several types by fluency and comprehension. Knowing the type helps in understanding the outlook, but the type itself is not the strongest predictor. The initial severity is:
Families can note one point: a type only becomes milder over time and does not become more severe. Pedersen and colleagues (2004) re-assessed 270 patients with aphasia after acute stroke one year later. They found that global aphasia made up about 32% in the acute phase and fell to about 7% after a year, and that anomic aphasia became the most common end state. Global can evolve into Wernicke or Broca, and Broca can evolve into anomic, but the reverse change to a more severe type does not happen. The table below compares the speed of recovery of the types.
- Broca (expressive): relatively better outlook for recovery within one year (Bakheit et al., 2007)
- Anomic: a milder end state, often the result of other types evolving
- Types as a whole only become milder and do not become more severe (Pedersen et al., 2004)
- Global: the most severe, but its improvement is still greater than that of Wernicke (Bakheit et al., 2007)
- Wernicke (receptive): improvement is relatively more limited
- The above are comparative statements and are not absolute percentages or a guarantee for any individual
Note that the abstract of Bakheit and colleagues (2007, 75 patients with a first stroke) gives only comparative statements, namely that Broca has a relatively better outlook and that global improves more than Wernicke. It gives no absolute percentages that can be cited, so this article does not list specific figures.
The benefit of speech therapy and room for progress in the chronic phase
The extent of recovery depends in part on therapy. As noted above, the Cochrane systematic review found that speech therapy clearly improved functional communication compared with no therapy (SMD 0.28), and also improved reading, writing and expressive language (Brady et al., 2016). The same review noted that groups with high intensity, high dose or a long course had better functional communication, but the drop-out rate in these high-intensity groups was also clearly higher, so intensive therapy is not acceptable to everyone. A larger amount of therapy is therefore not necessarily better for every patient.
Language ability can still improve after more than six months from the stroke. Many people wrongly believe that things are fixed six months after a stroke. A randomised controlled trial published in the Lancet (156 patients with chronic aphasia more than six months after stroke, given intensive speech therapy of at least 10 hours a week for three weeks) showed a clear improvement in everyday language communication (difference between groups 2.61 points, Cohen's d 0.58, p=0.0004; Breitenstein et al., 2017). This shows that even in the chronic phase, when natural recovery has slowed, enough hours of targeted therapy can still bring real progress.
How common aphasia is and natural recovery
Many families ask: "Without therapy, will it get better on its own?" Epidemiological data give some clues but need careful reading. The systematic review by Flowers and colleagues (2016) showed a median prevalence of aphasia of about 30% in the acute phase and about 34% in the rehabilitation phase of mixed stroke populations. Studies following patients for one year showed that the one-year prevalence of aphasia fell by about 2% to 12% from baseline, which reflects the improvement from natural recovery and from therapy.
Note that a fall of 2% to 12% is a fall in prevalence and is not an individual recovery rate. It cannot be read as X% of patients recovering fully. A fall in prevalence reflects a change in the proportion of aphasia across the whole population, mixing natural recovery, the effect of therapy and other factors, and cannot be converted into the chance of recovery for an individual patient. On whether the patient will recover naturally, the answer is therefore still that most people improve, but how far differs from person to person, and early, targeted therapy raises the chance of improvement.
Realistic expectations about full recovery from aphasia
The range of outlook. The outlook for aphasia varies widely and is decided mainly by the initial severity. Recovery from severe or global aphasia is relatively limited, and full recovery cannot be guaranteed (Plowman et al., 2012; Bakheit et al., 2007; Pedersen et al., 1995). On the other hand, even in the chronic phase, intensive and targeted therapy can still bring real progress (Breitenstein et al., 2017), so there is no need to think that there is no hope after six months. False reassurance should not be given, and neither should excessive pessimism. The final assessment of the outlook has to be made by a speech therapist for the individual patient, according to the severity, the damage and the course of recovery. This article gives only a framework for understanding and is not a prediction for any individual patient.